diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index a30cb4f0..bcfccb0d 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -60,10 +60,12 @@ module.exports = {
     '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
     '@typescript-eslint/no-shadow': 'error',
 
-    // Policy: kept as warnings, not errors. The codebase has ~70 long-standing
-    // `any` casts and ~15 non-null assertions in matrix-js-sdk interop code.
-    // Promoting to error would block builds on existing usage; turning off
-    // would lose signal on new code. Warnings are visible without blocking.
+    // Policy: kept as `warn` at the rule level so editors / `eslint --fix` /
+    // ad-hoc runs surface them as warnings, but `npm run check:eslint` and
+    // `lint-staged` BOTH pass `--max-warnings 0`, so new occurrences block
+    // commit. When unavoidable (matrix-js-sdk boundary, generic helpers,
+    // third-party callback shapes), suppress on the line with
+    // `// eslint-disable-next-line` and a one-line justification.
     '@typescript-eslint/no-explicit-any': 'warn',
     '@typescript-eslint/no-non-null-assertion': 'warn',
   },
@@ -86,6 +88,11 @@ module.exports = {
         'no-plusplus': 'off',
         'prefer-template': 'off',
         'no-param-reassign': 'off',
+        // `for (;;)` form upstream uses for the iter-loops trips eslint
+        // even though it's intentional — keep upstream control flow.
+        'no-constant-condition': 'off',
+        // Diagnostic `console.log` left as-is in vendor copy.
+        'no-console': 'off',
       },
     },
   ],
diff --git a/.husky/pre-commit b/.husky/pre-commit
old mode 100644
new mode 100755
index 7aea7a8d..e55b74d6
--- a/.husky/pre-commit
+++ b/.husky/pre-commit
@@ -1,3 +1,2 @@
-# These are commented until we enable lint and typecheck
-# npx tsc -p tsconfig.json --noEmit
-# npx lint-staged
\ No newline at end of file
+npx tsc -p tsconfig.json --noEmit
+npx lint-staged
diff --git a/docs/ai/architecture.md b/docs/ai/architecture.md
index 76c215e2..4e508589 100644
--- a/docs/ai/architecture.md
+++ b/docs/ai/architecture.md
@@ -11,7 +11,7 @@ npm run typecheck # tsc --noEmit
 
 Build: **Vite 5.4** with vanilla-extract, WASM, PWA plugins.
 
-> **Note:** `.husky/pre-commit` is currently commented out. `npm run check:eslint` is **green** (0 errors, 116 warnings — kept as warn for `no-explicit-any`/`no-non-null-assertion` policy). `npm run typecheck` still has ~32 known errors (residual project bugs after the TS 5.4 + Bundler migration that cleared ~800 module-resolution errors — see `docs/known-tech-debt-lint/`). Use `bash docs/known-tech-debt-lint/diff.sh` to verify your changes added no new typecheck errors, then `npm run build` for the green build check.
+> **Note:** `.husky/pre-commit` is enabled and runs `tsc --noEmit` + `lint-staged` (which calls `eslint --max-warnings 0` on staged JS/TS files). Both gates are zero: `npm run typecheck` and `npm run check:eslint` are green (0 errors, 0 warnings). Custom Matrix event-types (`AccountDataEvent.Vojo*`, `PoniesRoomEmotes`, `m.bridge`, `m.call.member` etc.) live in [`src/types/matrix/sdkAugmentation.d.ts`](../../src/types/matrix/sdkAugmentation.d.ts) — add new custom types there to keep `mx.getAccountData` / `mx.getStateEvent` calls type-safe.
 
 ## Source Layout
 
@@ -287,7 +287,7 @@ i18next + `react-i18next`. Translations in `public/locales/{en,ru}/*.json`, orga
 - Current vojo work branch: `vojo/dev`
 - Semantic-release on `dev` branch
 - CI: GitHub Actions (build, deploy, docker, netlify)
-- **Husky pre-commit is currently disabled** — `npm run typecheck` and `npm run check:eslint` do not run automatically. `check:eslint` is green; `typecheck` still has ~32 known errors. Use `bash docs/known-tech-debt-lint/diff.sh` to check your changes don't add new typecheck errors. Re-enable husky once typecheck residual is cleared.
+- **Husky pre-commit runs `tsc --noEmit` + `lint-staged` (`eslint --max-warnings 0`)** — both must be green to commit. `no-explicit-any` and `no-non-null-assertion` policy: kept as `'warn'` in `.eslintrc.cjs` but blocked by `--max-warnings 0`. When introducing one is unavoidable (matrix-js-sdk boundary, generic helper, third-party callback shape), add an inline `// eslint-disable-next-line` with a one-line justification rather than relaxing the rule.
 - **Android `versionCode` is monotonic** (commit 8064760, derived from commit count). Don't squash or rebase across release boundaries — Play store rejects downgrades
 - **Commit message style** (vojo memory): one sentence ≤25 words; no body; no Co-Authored-By trailer
 
diff --git a/docs/known-tech-debt-lint/README.md b/docs/known-tech-debt-lint/README.md
deleted file mode 100644
index 30ab6199..00000000
--- a/docs/known-tech-debt-lint/README.md
+++ /dev/null
@@ -1,57 +0,0 @@
-# Известный техдолг по линтеру
-
-Эта папка фиксирует **известное состояние** `npm run typecheck` в репозитории. Build при этом зелёный, prod задеплоен — это исторический технический долг, не блокер. Папка нужна чтобы при любых изменениях кода сравнивать **delta** (только то что мы добавили), не путаясь в предсуществующих ошибках.
-
-После апгрейда TypeScript 4.9 → 5.4 + `moduleResolution: "Bundler"` (см. историю коммита) основная масса (~803 из 835 предыдущих ошибок) исчезла. Осталось ~32 ошибки уже про реальные баги/несоответствия типов в нашем коде, не про модульное резолвинг. `npm run check:eslint` теперь — обычный зелёный чек (0 ошибок, 116 warnings), отдельный snapshot не нужен.
-
-## Состав
-
-| Файл | Что |
-|---|---|
-| `typecheck.snapshot.txt` | Полный stdout `npm run typecheck`. **~61 строка, ~32 ошибки.** |
-| `diff.sh` | Скрипт сравнения: запускает текущий typecheck, сравнивает с snapshot-ом, выдаёт **только delta**. |
-
-## Как пользоваться
-
-```bash
-bash docs/known-tech-debt-lint/diff.sh
-```
-
-На чистой ветке выводит:
-```
-=== typecheck diff vs known-tech-debt snapshot ===
-  no new typecheck errors
-```
-
-Если что-то сломал — выводит конкретные новые ошибки в формате `file.tsx(_,_): error TS...` (line/col маска чтобы pure-line-shift не давал phantom NEW + fixed). Реальные позиции — `npm run typecheck` напрямую. Если случайно починил предсуществующий долг — отчитается «(incidentally fixed: N)» к сведению.
-
-Скрипт смотрит **working tree**, не staged-состояние. Для строгого pre-commit gate сначала apply'нуть свой stage в чистый worktree (`git stash --keep-index` + `bash diff.sh` + `git stash pop`).
-
-`npm run check:eslint` запускайте напрямую — он зелёный.
-
-## Что в долге (TL;DR)
-
-**Typecheck (~32 ошибок):** реальные несоответствия типов. Категории:
-
-- TS2345 keyof literal-union mismatch (~14): `mx.getAccountData(string)` / `mx.getStateEvent(...)` ждёт `keyof AccountDataEvents` (узкие литеральные типы), у нас передаются `AccountDataEvent.PoniesEmoteRooms`, `'m.call.member'`, `'in.cinny.spaces'` и т.п. — валидные Matrix event-types, но не в SDK-юнионе.
-- TS2345 i18next signature (~3): `t('Room.members_count', { count: millify(...) })` — `count` хочет `number`, а `millify()` возвращает `string`. На рантайме отображается корректно (в локалях нет plural-вариантов).
-- TS2345 / TS18048 `Room | undefined` / `Room | null` после `.filter((r) => !!r)` (~6): TS не пропускает truthy-фильтр без type predicate. UserChips.tsx, AddExisting.tsx, Invites.tsx, GlobalPacks.tsx. Runtime безопасно.
-- TS2345 `IContent` → `RoomMessageEventContent` (1): MessageEditor.tsx — typing gap между общим content и room-message variant.
-- TS7006 implicit `any` (6): event-handler params (`evt`, `event`, `ev`) в Message.tsx, EventReaders.tsx, UrlPreviewCard.tsx, LiveChip.tsx, MemberGlance.tsx, ReactionViewer.tsx.
-- TS2540 read-only `sandbox` (1): CallEmbed.ts — `iframe.sandbox = "..."`. Современные DOM types сделали его `DOMTokenList` read-only, но браузеры всё ещё принимают строку.
-- TS2353 unknown property `endpoint` (1): push.ts — лишнее поле в `setPusher.data`. SDK типы неполные, sygnal/UnifiedPush его читает.
-- TS2322 `(number | undefined)[]` → `number[]` (1): usePowerLevelTags.ts — то же truthy-filter narrowing.
-
-Build зелёный, ESLint зелёный. Все 32 оставшихся ошибки — type-strictness без runtime-импакта (truthy-filter narrowing, узкие SDK literal-union'ы, под-типированные event-handler params, слишком строгий DOM types). Это **известный долг**, не блокер. Будущая чистка — отдельный план (создать `docs/plans/typecheck_residual_cleanup.md` когда возьмёмся).
-
-## Когда обновлять snapshot
-
-Когда долг будет частично разруливаться отдельной задачей — после её мерджа пересоздать snapshot:
-
-```bash
-npm run typecheck > docs/known-tech-debt-lint/typecheck.snapshot.txt 2>&1
-```
-
-И обновить TL;DR в этом README.
-
-Когда typecheck станет зелёным — удалить эту папку целиком и включить husky pre-commit hook.
diff --git a/docs/known-tech-debt-lint/diff.sh b/docs/known-tech-debt-lint/diff.sh
deleted file mode 100755
index fa8383bc..00000000
--- a/docs/known-tech-debt-lint/diff.sh
+++ /dev/null
@@ -1,91 +0,0 @@
-#!/usr/bin/env bash
-# Compare current `npm run typecheck` output to the known tech-debt snapshot.
-# Emits ONLY new errors introduced relative to the snapshot — does not dump
-# the full output, so agents can read the result without burning context.
-#
-# Comparison is line/col-insensitive: each error's `(L,C):` location is masked
-# to `(_,_):` before sorting + comm, so a pure line shift (e.g. one added/
-# removed line above the error) doesn't trigger a phantom NEW + fixed pair.
-# Re-run `npm run typecheck` to see real positions for any errors flagged here.
-#
-# Caveat: this checks the working tree, not the staged worktree. If you stage
-# a fix but leave it unstaged, or vice versa, the diff reports the working-tree
-# state. For a strict pre-commit gate, run from a clean stash-apply state.
-#
-# `npm run check:eslint` is now a normal green check (0 errors); no snapshot
-# needed there. Run it directly if you want to see warnings.
-#
-# Usage:
-#   bash docs/known-tech-debt-lint/diff.sh
-
-set -u
-
-ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
-BASELINE_DIR="$ROOT/docs/known-tech-debt-lint"
-TC_BASE="$BASELINE_DIR/typecheck.snapshot.txt"
-
-# Temp files registered for cleanup on any exit path (success, error, ^C).
-TMP_FILES=()
-cleanup() { [ "${#TMP_FILES[@]}" -gt 0 ] && rm -f "${TMP_FILES[@]}"; }
-trap cleanup EXIT INT TERM
-
-# Tracks whether any new errors were introduced. Set to 1 by run_typecheck_diff
-# when delta > 0; script exits with this code at end so CI / runbooks can use
-# the script as a gate (e.g. `bash diff.sh && echo OK`).
-NEW_ERRORS=0
-
-run_typecheck_diff() {
-  echo "=== typecheck diff vs known-tech-debt snapshot ==="
-  local now tc_rc
-  now="$(mktemp)"
-  TMP_FILES+=("$now")
-  ( cd "$ROOT" && npm run typecheck ) >"$now" 2>&1
-  tc_rc=$?
-  # Sanity-check: distinguish "tsc ran and reported errors" (rc=2, expected on
-  # this baseline) from "tsc/npm/node failed to run at all" (rc=other, broken
-  # toolchain). Without this guard a rc=127 "tsc: not found" or rc=1 npm error
-  # could produce stdout with no "error TS" lines and the diff would falsely
-  # report "no new errors" / "incidentally fixed: 33".
-  if [ "$tc_rc" -ne 0 ] && [ "$tc_rc" -ne 2 ] && ! grep -q "error TS" "$now"; then
-    echo "  ERROR: 'npm run typecheck' did not run cleanly (exit=$tc_rc):"
-    sed 's/^/    /' "$now"
-    NEW_ERRORS=2
-    return
-  fi
-  # Mask `(line,col):` so a pure line shift doesn't change an error's identity.
-  # We compare on the masked form; for NEW lines we display the masked form (the
-  # real position is reproducible by running `npm run typecheck` directly).
-  # `sort` (NOT `sort -u`): we want to preserve cardinality so that two identical
-  # masked errors in the same file aren't collapsed to one — a regression that
-  # adds a duplicate error would otherwise be hidden by the first occurrence.
-  local mask_re='s/\([0-9]+,[0-9]+\):/(_,_):/'
-  local now_masked base_masked
-  now_masked="$(mktemp)"
-  base_masked="$(mktemp)"
-  TMP_FILES+=("$now_masked" "$base_masked")
-  sed -E "$mask_re" "$now"     | grep -E "error TS" | sort > "$now_masked"
-  sed -E "$mask_re" "$TC_BASE" | grep -E "error TS" | sort > "$base_masked"
-
-  local new
-  new="$(comm -23 "$now_masked" "$base_masked")"
-  if [ -z "$new" ]; then
-    echo "  no new typecheck errors"
-  else
-    local count
-    count="$(printf '%s\n' "$new" | wc -l)"
-    echo "  NEW errors: $count (line/col masked — run \`npm run typecheck\` for real positions)"
-    printf '%s\n' "$new" | sed 's/^/    /'
-    NEW_ERRORS=1
-  fi
-  local fixed
-  fixed="$(comm -13 "$now_masked" "$base_masked")"
-  if [ -n "$fixed" ]; then
-    local fcount
-    fcount="$(printf '%s\n' "$fixed" | wc -l)"
-    echo "  (incidentally fixed: $fcount)"
-  fi
-}
-
-run_typecheck_diff
-
-exit "$NEW_ERRORS"
diff --git a/docs/known-tech-debt-lint/typecheck.snapshot.txt b/docs/known-tech-debt-lint/typecheck.snapshot.txt
deleted file mode 100644
index 2b2a66ea..00000000
--- a/docs/known-tech-debt-lint/typecheck.snapshot.txt
+++ /dev/null
@@ -1,54 +0,0 @@
-
-> vojo@4.11.1 typecheck
-> tsc --noEmit
-
-src/app/components/event-readers/EventReaders.tsx(82,31): error TS7006: Parameter 'event' implicitly has an 'any' type.
-src/app/components/image-pack-view/RoomImagePack.tsx(47,9): error TS2345: Argument of type 'StateEvent.PoniesRoomEmotes' is not assignable to parameter of type 'keyof StateEvents'.
-src/app/components/image-pack-view/UserImagePack.tsx(16,31): error TS2345: Argument of type 'AccountDataEvent.PoniesUserEmotes' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/components/room-card/RoomCard.tsx(259,18): error TS2345: Argument of type '["Explore.members_count", { count: string; }]' is not assignable to parameter of type '[key: string | string[], options: TOptionsBase & $Dictionary & { defaultValue: string; }] | [key: string | string[], defaultValue: string, options?: (TOptionsBase & $Dictionary) | undefined] | [key: ...]'.
-  Type '["Explore.members_count", { count: string; }]' is not assignable to type '[key: "Explore.members_count" | "Explore.members_count"[], options?: (TOptionsBase & $Dictionary) | undefined]'.
-    Type at position 1 in source is not compatible with type at position 1 in target.
-      Type '{ count: string; }' is not assignable to type 'TOptionsBase & $Dictionary'.
-        Type '{ count: string; }' is not assignable to type 'TOptionsBase'.
-          Types of property 'count' are incompatible.
-            Type 'string' is not assignable to type 'number'.
-src/app/components/url-preview/UrlPreviewCard.tsx(57,27): error TS7006: Parameter 'evt' implicitly has an 'any' type.
-src/app/components/user-profile/UserChips.tsx(271,13): error TS18048: 'room' is possibly 'undefined'.
-src/app/components/user-profile/UserChips.tsx(272,28): error TS2345: Argument of type 'Room | undefined' is not assignable to parameter of type 'Room'.
-  Type 'undefined' is not assignable to type 'Room'.
-src/app/components/user-profile/UserChips.tsx(275,26): error TS18048: 'room' is possibly 'undefined'.
-src/app/components/user-profile/UserChips.tsx(276,29): error TS2345: Argument of type 'Room | undefined' is not assignable to parameter of type 'Room'.
-  Type 'undefined' is not assignable to type 'Room'.
-src/app/components/user-profile/UserChips.tsx(279,25): error TS2345: Argument of type 'Room | undefined' is not assignable to parameter of type 'Room'.
-  Type 'undefined' is not assignable to type 'Room'.
-src/app/features/add-existing/AddExisting.tsx(168,18): error TS2345: Argument of type '(Room | undefined)[]' is not assignable to parameter of type 'Room[]'.
-  Type 'Room | undefined' is not assignable to type 'Room'.
-    Type 'undefined' is not assignable to type 'Room'.
-src/app/features/call-status/LiveChip.tsx(90,35): error TS7006: Parameter 'evt' implicitly has an 'any' type.
-src/app/features/call-status/MemberGlance.tsx(49,23): error TS7006: Parameter 'evt' implicitly has an 'any' type.
-src/app/features/common-settings/general/RoomJoinRules.tsx(92,52): error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
-  Type 'undefined' is not assignable to type 'string'.
-src/app/features/room/message/Message.tsx(860,31): error TS7006: Parameter 'ev' implicitly has an 'any' type.
-src/app/features/room/message/MessageEditor.tsx(156,39): error TS2345: Argument of type 'IContent' is not assignable to parameter of type 'RoomMessageEventContent'.
-  Type 'IContent' is not assignable to type 'BaseTimelineEvent & Without<(Without<ReplyEvent, NoRelationEvent> & NoRelationEvent) | (Without<NoRelationEvent, ReplyEvent> & ReplyEvent), (Without<...> & RelationEvent) | (Without<...> & ReplacementEvent<...>)> & Without<...> & ReplacementEvent<...> & FileContent'.
-    Property '"body"' is missing in type 'IContent' but required in type 'BaseTimelineEvent'.
-src/app/features/room/reaction-viewer/ReactionViewer.tsx(135,33): error TS7006: Parameter 'event' implicitly has an 'any' type.
-src/app/features/settings/developer-tools/DevelopTools.tsx(30,31): error TS2345: Argument of type 'string' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/features/settings/developer-tools/DevelopTools.tsx(39,54): error TS2345: Argument of type 'string' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/features/settings/emojis-stickers/GlobalPacks.tsx(161,44): error TS2345: Argument of type '(PackAddress | undefined)[]' is not assignable to parameter of type 'PackAddress[]'.
-  Type 'PackAddress | undefined' is not assignable to type 'PackAddress'.
-    Type 'undefined' is not assignable to type 'PackAddress'.
-src/app/features/settings/emojis-stickers/GlobalPacks.tsx(164,39): error TS2345: Argument of type '(PackAddress | undefined)[]' is not assignable to parameter of type 'PackAddress[]'.
-src/app/features/settings/emojis-stickers/GlobalPacks.tsx(311,27): error TS2345: Argument of type 'AccountDataEvent.PoniesEmoteRooms' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/features/settings/emojis-stickers/GlobalPacks.tsx(328,31): error TS2345: Argument of type 'AccountDataEvent.PoniesEmoteRooms' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/hooks/useAccountData.ts(7,62): error TS2345: Argument of type 'string' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/hooks/usePowerLevelTags.ts(14,9): error TS2322: Type '(number | undefined)[]' is not assignable to type 'number[]'.
-  Type 'number | undefined' is not assignable to type 'number'.
-    Type 'undefined' is not assignable to type 'number'.
-src/app/pages/client/inbox/Invites.tsx(722,45): error TS2345: Argument of type 'Room | null' is not assignable to parameter of type 'Room'.
-  Type 'null' is not assignable to type 'Room'.
-src/app/pages/client/sidebar/SpaceTabs.tsx(750,27): error TS2345: Argument of type 'AccountDataEvent.VojoSpaces' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/pages/client/sidebar/SpaceTabs.tsx(797,25): error TS2345: Argument of type 'AccountDataEvent.VojoSpaces' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/plugins/call/CallEmbed.ts(129,12): error TS2540: Cannot assign to 'sandbox' because it is a read-only property.
-src/app/plugins/recent-emoji.ts(45,21): error TS2345: Argument of type 'AccountDataEvent.ElementRecentEmoji' is not assignable to parameter of type 'keyof AccountDataEvents'.
-src/app/utils/push.ts(160,9): error TS2353: Object literal may only specify known properties, and 'endpoint' does not exist in type '{ format?: string | undefined; url?: string | undefined; brand?: string | undefined; }'.
diff --git a/package.json b/package.json
index 59ab8424..2cc3415b 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
     "build": "vite build",
     "preview": "vite preview",
     "lint": "npm run check:eslint && npm run check:prettier",
-    "check:eslint": "eslint src",
+    "check:eslint": "eslint --max-warnings 0 src",
     "check:prettier": "prettier --check .",
     "fix:prettier": "prettier --write .",
     "typecheck": "tsc --noEmit",
@@ -30,7 +30,7 @@
     "commit": "git-cz"
   },
   "lint-staged": {
-    "*.{ts,tsx,js,jsx,mjs,cjs}": "eslint",
+    "*.{ts,tsx,js,jsx,mjs,cjs}": "eslint --max-warnings 0",
     "*": "prettier --ignore-unknown --write"
   },
   "config": {
diff --git a/public/locales/en.json b/public/locales/en.json
index ee0e114f..ece119a5 100644
--- a/public/locales/en.json
+++ b/public/locales/en.json
@@ -647,7 +647,8 @@
     "no_communities": "No communities found!",
 
     "space_badge": "Space",
-    "members_count": "{{count}} Members",
+    "members_count_one": "{{formattedCount}} Member",
+    "members_count_other": "{{formattedCount}} Members",
     "join": "Join",
     "joining": "Joining",
     "retry": "Retry",
diff --git a/public/locales/ru.json b/public/locales/ru.json
index 4e20a631..b4200f4e 100644
--- a/public/locales/ru.json
+++ b/public/locales/ru.json
@@ -661,7 +661,10 @@
     "no_communities": "Сообщества не найдены!",
 
     "space_badge": "Пространство",
-    "members_count": "{{count}} участников",
+    "members_count_one": "{{formattedCount}} участник",
+    "members_count_few": "{{formattedCount}} участника",
+    "members_count_many": "{{formattedCount}} участников",
+    "members_count_other": "{{formattedCount}} участника",
     "join": "Присоединиться",
     "joining": "Вступление…",
     "retry": "Повторить",
diff --git a/src/app/components/ActionUIA.tsx b/src/app/components/ActionUIA.tsx
index b9cd122f..608f283e 100644
--- a/src/app/components/ActionUIA.tsx
+++ b/src/app/components/ActionUIA.tsx
@@ -36,7 +36,7 @@ export function ActionUIA({ authData, ongoingFlow, action, onCancel }: ActionUIA
     >
       {stageToComplete.type === AuthType.Password && (
         <PasswordStage
-          userId={mx.getUserId()!}
+          userId={mx.getSafeUserId()}
           stageData={stageToComplete}
           onCancel={onCancel}
           submitAuthDict={action}
diff --git a/src/app/components/DeviceVerificationSetup.tsx b/src/app/components/DeviceVerificationSetup.tsx
index 433fa6a1..0769402e 100644
--- a/src/app/components/DeviceVerificationSetup.tsx
+++ b/src/app/components/DeviceVerificationSetup.tsx
@@ -42,7 +42,7 @@ function makeUIAAction<T>(
   authData: IAuthData,
   performAction: PerformAction<T>,
   resolve: (data: T) => void,
-  reject: (error?: any) => void
+  reject: (error?: unknown) => void
 ): UIAAction<T> {
   const action: UIAAction<T> = {
     authData,
diff --git a/src/app/components/ImageOverlay.tsx b/src/app/components/ImageOverlay.tsx
index ea690924..d87f934b 100644
--- a/src/app/components/ImageOverlay.tsx
+++ b/src/app/components/ImageOverlay.tsx
@@ -30,7 +30,7 @@ export const ImageOverlay = as<'div', ImageOverlayProps>(
           <Modal
             className={ModalWide}
             size="500"
-            onContextMenu={(evt: any) => evt.stopPropagation()}
+            onContextMenu={(evt: React.MouseEvent<HTMLDivElement>) => evt.stopPropagation()}
           >
             {renderViewer({
               src,
diff --git a/src/app/components/SecretStorage.tsx b/src/app/components/SecretStorage.tsx
index 9d8628e5..815f5fbc 100644
--- a/src/app/components/SecretStorage.tsx
+++ b/src/app/components/SecretStorage.tsx
@@ -39,6 +39,8 @@ export function SecretStorageRecoveryPassphrase({
           bits
         );
 
+        // matrix-js-sdk wants SecretStorageKeyDescriptionAesV1; our local type is structurally compatible but distinct.
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
         const match = await mx.secretStorage.checkKey(decodedRecoveryKey, keyContent as any);
 
         if (!match) {
@@ -131,6 +133,8 @@ export function SecretStorageRecoveryKey({
       async (recoveryKey) => {
         const decodedRecoveryKey = decodeRecoveryKey(recoveryKey);
 
+        // matrix-js-sdk wants SecretStorageKeyDescriptionAesV1; our local type is structurally compatible but distinct.
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
         const match = await mx.secretStorage.checkKey(decodedRecoveryKey, keyContent as any);
 
         if (!match) {
diff --git a/src/app/components/ServerConfigsLoader.tsx b/src/app/components/ServerConfigsLoader.tsx
index 3c8ce8eb..ddd198bb 100644
--- a/src/app/components/ServerConfigsLoader.tsx
+++ b/src/app/components/ServerConfigsLoader.tsx
@@ -34,6 +34,9 @@ export function ServerConfigsLoader({ children }: ServerConfigsLoaderProps) {
       try {
         validatedAuthMetadata = validateAuthMetadata(authMetadata);
       } catch (e) {
+        // Auth-metadata parsing failure is non-fatal; the client falls
+        // back to legacy `.well-known` discovery. Surface to dev console.
+        // eslint-disable-next-line no-console
         console.error(e);
       }
 
diff --git a/src/app/components/create-room/utils.ts b/src/app/components/create-room/utils.ts
index f3e699aa..4f7d6be1 100644
--- a/src/app/components/create-room/utils.ts
+++ b/src/app/components/create-room/utils.ts
@@ -6,6 +6,7 @@ import {
   RestrictedAllowType,
   Room,
 } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { RoomJoinRulesEventContent } from 'matrix-js-sdk/lib/types';
 import { RoomType, StateEvent } from '../../../types/matrix/room';
 import { getViaServers } from '../../plugins/via-servers';
@@ -17,7 +18,7 @@ export const createRoomCreationContent = (
   allowFederation: boolean,
   additionalCreators: string[] | undefined
 ): object => {
-  const content: Record<string, any> = {};
+  const content: Record<string, unknown> = {};
   if (typeof type === 'string') {
     content.type = type;
   }
@@ -152,11 +153,11 @@ export const createRoom = async (mx: MatrixClient, data: CreateRoomData): Promis
   if (data.parent) {
     await mx.sendStateEvent(
       data.parent.roomId,
-      StateEvent.SpaceChild as any,
+      StateEvent.SpaceChild as keyof StateEvents,
       {
         auto_join: false,
         suggested: false,
-        via: [getMxIdServer(mx.getUserId() ?? '') ?? ''],
+        via: [getMxIdServer(mx.getSafeUserId()) ?? ''],
       },
       result.room_id
     );
diff --git a/src/app/components/editor/autocomplete/RoomMentionAutocomplete.tsx b/src/app/components/editor/autocomplete/RoomMentionAutocomplete.tsx
index 377cecab..de5b9b10 100644
--- a/src/app/components/editor/autocomplete/RoomMentionAutocomplete.tsx
+++ b/src/app/components/editor/autocomplete/RoomMentionAutocomplete.tsx
@@ -24,7 +24,7 @@ type MentionAutoCompleteHandler = (roomAliasOrId: string, name: string) => void;
 const roomAliasFromQueryText = (mx: MatrixClient, text: string) =>
   isRoomAlias(`#${text}`)
     ? `#${text}`
-    : `#${text}${text.endsWith(':') ? '' : ':'}${getMxIdServer(mx.getUserId() ?? '')}`;
+    : `#${text}${text.endsWith(':') ? '' : ':'}${getMxIdServer(mx.getSafeUserId())}`;
 
 function UnknownRoomMentionItem({
   query,
diff --git a/src/app/components/editor/autocomplete/UserMentionAutocomplete.tsx b/src/app/components/editor/autocomplete/UserMentionAutocomplete.tsx
index 7a8012eb..dc446137 100644
--- a/src/app/components/editor/autocomplete/UserMentionAutocomplete.tsx
+++ b/src/app/components/editor/autocomplete/UserMentionAutocomplete.tsx
@@ -26,7 +26,7 @@ type MentionAutoCompleteHandler = (userId: string, name: string) => void;
 const userIdFromQueryText = (mx: MatrixClient, text: string) =>
   isUserId(`@${text}`)
     ? `@${text}`
-    : `@${text}${text.endsWith(':') ? '' : ':'}${getMxIdServer(mx.getUserId() ?? '')}`;
+    : `@${text}${text.endsWith(':') ? '' : ':'}${getMxIdServer(mx.getSafeUserId())}`;
 
 function UnknownMentionItem({
   userId,
@@ -92,7 +92,7 @@ export function UserMentionAutocomplete({
 }: UserMentionAutocompleteProps) {
   const mx = useMatrixClient();
   const useAuthentication = useMediaAuthentication();
-  const roomId: string = room.roomId!;
+  const { roomId } = room;
   const roomAliasOrId = room.getCanonicalAlias() || roomId;
   const members = useRoomMembers(mx, roomId);
 
diff --git a/src/app/components/event-readers/EventReaders.tsx b/src/app/components/event-readers/EventReaders.tsx
index c7900237..fbbba81c 100644
--- a/src/app/components/event-readers/EventReaders.tsx
+++ b/src/app/components/event-readers/EventReaders.tsx
@@ -79,7 +79,7 @@ export const EventReaders = as<'div', EventReadersProps>(
                     key={readerId}
                     style={{ padding: `0 ${config.space.S200}` }}
                     radii="400"
-                    onClick={(event) => {
+                    onClick={(event: React.MouseEvent<HTMLButtonElement>) => {
                       openProfile(
                         room.roomId,
                         space?.roomId,
diff --git a/src/app/components/image-pack-view/RoomImagePack.tsx b/src/app/components/image-pack-view/RoomImagePack.tsx
index 92b4ff21..50e32ad7 100644
--- a/src/app/components/image-pack-view/RoomImagePack.tsx
+++ b/src/app/components/image-pack-view/RoomImagePack.tsx
@@ -17,7 +17,7 @@ type RoomImagePackProps = {
 
 export function RoomImagePack({ room, stateKey }: RoomImagePackProps) {
   const mx = useMatrixClient();
-  const userId = mx.getUserId()!;
+  const userId = mx.getSafeUserId();
   const powerLevels = usePowerLevels(room);
   const creators = useRoomCreators(room);
 
diff --git a/src/app/components/image-pack-view/UserImagePack.tsx b/src/app/components/image-pack-view/UserImagePack.tsx
index 4987793d..2c46b07c 100644
--- a/src/app/components/image-pack-view/UserImagePack.tsx
+++ b/src/app/components/image-pack-view/UserImagePack.tsx
@@ -8,7 +8,7 @@ import { useUserImagePack } from '../../hooks/useImagePacks';
 export function UserImagePack() {
   const mx = useMatrixClient();
 
-  const defaultPack = useMemo(() => new ImagePack(mx.getUserId() ?? '', {}, undefined), [mx]);
+  const defaultPack = useMemo(() => new ImagePack(mx.getSafeUserId(), {}, undefined), [mx]);
   const imagePack = useUserImagePack();
 
   const handleUpdate = useCallback(
diff --git a/src/app/components/message/attachment/StreamMediaShell.tsx b/src/app/components/message/attachment/StreamMediaShell.tsx
index f1e1388d..10cd6026 100644
--- a/src/app/components/message/attachment/StreamMediaShell.tsx
+++ b/src/app/components/message/attachment/StreamMediaShell.tsx
@@ -32,6 +32,8 @@ function computeBoxStyle(naturalW?: number, naturalH?: number): React.CSSPropert
   // `object-fit: cover` (image) / `contain` (video) on the inner element.
   const naturalAspect = naturalW && naturalH ? naturalW / naturalH : NaN;
   if (
+    !naturalW ||
+    !naturalH ||
     !Number.isFinite(naturalAspect) ||
     naturalAspect < STREAM_MEDIA_MIN_ASPECT ||
     naturalAspect > STREAM_MEDIA_MAX_ASPECT
@@ -39,10 +41,10 @@ function computeBoxStyle(naturalW?: number, naturalH?: number): React.CSSPropert
     return { width: toRem(STREAM_MEDIA_MAX_DIM), height: toRem(STREAM_MEDIA_MAX_DIM) };
   }
   if (naturalAspect >= 1) {
-    const w = Math.min(STREAM_MEDIA_MAX_DIM, naturalW!);
+    const w = Math.min(STREAM_MEDIA_MAX_DIM, naturalW);
     return { width: toRem(w), height: toRem(w / naturalAspect) };
   }
-  const h = Math.min(STREAM_MEDIA_MAX_DIM, naturalH!);
+  const h = Math.min(STREAM_MEDIA_MAX_DIM, naturalH);
   return { width: toRem(h * naturalAspect), height: toRem(h) };
 }
 
diff --git a/src/app/components/message/content/FileContent.tsx b/src/app/components/message/content/FileContent.tsx
index 7e127f2a..b6ae97e3 100644
--- a/src/app/components/message/content/FileContent.tsx
+++ b/src/app/components/message/content/FileContent.tsx
@@ -114,7 +114,7 @@ export function ReadTextFile({ body, mimeType, url, encInfo, renderViewer }: Rea
               <Modal
                 className={ModalWide}
                 size="500"
-                onContextMenu={(evt: any) => evt.stopPropagation()}
+                onContextMenu={(evt: React.MouseEvent<HTMLDivElement>) => evt.stopPropagation()}
               >
                 {renderViewer({
                   name: body,
@@ -203,7 +203,7 @@ export function ReadPdfFile({ body, mimeType, url, encInfo, renderViewer }: Read
               <Modal
                 className={ModalWide}
                 size="500"
-                onContextMenu={(evt: any) => evt.stopPropagation()}
+                onContextMenu={(evt: React.MouseEvent<HTMLDivElement>) => evt.stopPropagation()}
               >
                 {renderViewer({
                   name: body,
diff --git a/src/app/components/message/content/ImageContent.tsx b/src/app/components/message/content/ImageContent.tsx
index 90122b24..bf10c0ad 100644
--- a/src/app/components/message/content/ImageContent.tsx
+++ b/src/app/components/message/content/ImageContent.tsx
@@ -177,7 +177,7 @@ export const ImageContent = as<'div', ImageContentProps>(
                 <Modal
                   className={ModalWide}
                   size="500"
-                  onContextMenu={(evt: any) => evt.stopPropagation()}
+                  onContextMenu={(evt: React.MouseEvent<HTMLDivElement>) => evt.stopPropagation()}
                 >
                   {renderViewer({
                     src: srcState.data,
@@ -214,10 +214,7 @@ export const ImageContent = as<'div', ImageContentProps>(
         )}
         {srcState.status === AsyncStatus.Success && (
           <Box
-            className={classNames(
-              css.AbsoluteContainer,
-              blurred ? css.Blur : css.ImageClickable
-            )}
+            className={classNames(css.AbsoluteContainer, blurred ? css.Blur : css.ImageClickable)}
           >
             {renderImage({
               alt: body,
diff --git a/src/app/components/page/Page.tsx b/src/app/components/page/Page.tsx
index d4007983..ab077687 100644
--- a/src/app/components/page/Page.tsx
+++ b/src/app/components/page/Page.tsx
@@ -15,11 +15,7 @@ import classNames from 'classnames';
 import { ContainerColor } from '../../styles/ContainerColor.css';
 import * as css from './style.css';
 import { ScreenSize, useScreenSizeContext } from '../../hooks/useScreenSize';
-import {
-  SIDEBAR_WIDTH_MIN,
-  clampSidebarWidth,
-  sidebarWidthAtom,
-} from '../../state/sidebarWidth';
+import { SIDEBAR_WIDTH_MIN, clampSidebarWidth, sidebarWidthAtom } from '../../state/sidebarWidth';
 import {
   VOJO_HORSESHOE_VOID_COLOR,
   VOJO_HORSESHOE_GAP_PX,
@@ -84,10 +80,7 @@ export function PageRoot({ nav, children }: PageRootProps) {
             apparent colour unchanged for routes whose content has no
             opaque bg of its own (e.g. ChannelsLanding) — without it
             the outer void would bleed through. */}
-        <Box
-          grow="Yes"
-          style={{ minWidth: 0, backgroundColor: VOJO_HORSESHOE_VOID_COLOR }}
-        >
+        <Box grow="Yes" style={{ minWidth: 0, backgroundColor: VOJO_HORSESHOE_VOID_COLOR }}>
           <Box
             grow="Yes"
             className={ContainerColor({ variant: 'Background' })}
@@ -147,6 +140,9 @@ export function PageNav({
   const horseshoe = useHorseshoeEnabled();
 
   if (resizable && !isMobile) {
+    // `ResizablePageNav` is a function declaration (hoisted) below — the
+    // forward reference is safe at runtime.
+    // eslint-disable-next-line no-use-before-define
     return <ResizablePageNav>{children}</ResizablePageNav>;
   }
 
@@ -160,9 +156,7 @@ export function PageNav({
   // we can override the default `Background.Container` without
   // touching the recipe.
   const surfaceStyle =
-    surface === 'surfaceVariant'
-      ? { backgroundColor: color.SurfaceVariant.Container }
-      : undefined;
+    surface === 'surfaceVariant' ? { backgroundColor: color.SurfaceVariant.Container } : undefined;
 
   return (
     <Box
@@ -199,9 +193,7 @@ function ResizablePageNav({ children }: { children: ReactNode }) {
   const handleRef = useRef<HTMLDivElement>(null);
   const horseshoe = useHorseshoeEnabled();
   const [savedWidth, setSavedWidth] = useAtom(sidebarWidthAtom);
-  const [vw, setVw] = useState<number>(
-    typeof window !== 'undefined' ? window.innerWidth : 1280
-  );
+  const [vw, setVw] = useState<number>(typeof window !== 'undefined' ? window.innerWidth : 1280);
   const [dragging, setDragging] = useState(false);
   // Live width during a drag — kept in component state so we don't write to
   // the localStorage-backed atom on every pointermove (hundreds of sync disk
@@ -322,6 +314,11 @@ function ResizablePageNav({ children }: { children: ReactNode }) {
         {children}
       </Box>
       {canResize && (
+        // Canonical WAI-ARIA window-splitter pattern: focusable separator
+        // with aria-orientation and current/min/max values. The strict
+        // role-supports-aria-props lookup table doesn't model the splitter
+        // sub-pattern, but assistive tech does.
+        // eslint-disable-next-line jsx-a11y/no-noninteractive-element-interactions, jsx-a11y/role-supports-aria-props, jsx-a11y/no-noninteractive-tabindex
         <div
           ref={handleRef}
           role="separator"
@@ -330,6 +327,7 @@ function ResizablePageNav({ children }: { children: ReactNode }) {
           aria-valuemin={SIDEBAR_WIDTH_MIN}
           aria-valuemax={maxW}
           aria-label="Resize sidebar"
+          // eslint-disable-next-line jsx-a11y/no-noninteractive-tabindex
           tabIndex={0}
           className={css.PageNavResizeHandle}
           // On web the page-nav is followed by the horseshoe void gap
diff --git a/src/app/components/room-card/RoomCard.tsx b/src/app/components/room-card/RoomCard.tsx
index e1d68193..577f5088 100644
--- a/src/app/components/room-card/RoomCard.tsx
+++ b/src/app/components/room-card/RoomCard.tsx
@@ -256,7 +256,10 @@ export const RoomCard = as<'div', RoomCardProps>(
           <Box gap="100">
             <Icon size="50" src={Icons.User} />
             <Text size="T200">
-              {t('Explore.members_count', { count: millify(joinedMemberCount) })}
+              {t('Explore.members_count', {
+                count: joinedMemberCount,
+                formattedCount: millify(joinedMemberCount),
+              })}
             </Text>
           </Box>
         )}
diff --git a/src/app/components/url-preview/UrlPreviewCard.tsx b/src/app/components/url-preview/UrlPreviewCard.tsx
index ee8967af..bc53c71f 100644
--- a/src/app/components/url-preview/UrlPreviewCard.tsx
+++ b/src/app/components/url-preview/UrlPreviewCard.tsx
@@ -54,7 +54,7 @@ export const UrlPreviewCard = as<'div', { url: string; ts: number }>(
               alt={prev['og:title']}
               title={prev['og:title']}
               tabIndex={0}
-              onKeyDown={(evt) => onEnterOrSpace(() => setViewer(true))(evt)}
+              onKeyDown={(evt: React.KeyboardEvent) => onEnterOrSpace(() => setViewer(true))(evt)}
               onClick={() => setViewer(true)}
             />
           )}
diff --git a/src/app/features/add-existing/AddExisting.tsx b/src/app/features/add-existing/AddExisting.tsx
index d100096b..6b4aecc2 100644
--- a/src/app/features/add-existing/AddExisting.tsx
+++ b/src/app/features/add-existing/AddExisting.tsx
@@ -30,6 +30,7 @@ import React, {
 import { useAtomValue } from 'jotai';
 import { useVirtualizer } from '@tanstack/react-virtual';
 import { Room } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { stopPropagation } from '../../utils/keyboard';
 import { useDirects, useRooms, useSpaces } from '../../state/hooks/roomList';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
@@ -136,7 +137,7 @@ export function AddExistingModal({ parentId, space, requestClose }: AddExistingM
 
           await mx.sendStateEvent(
             parentId,
-            StateEvent.SpaceChild as any,
+            StateEvent.SpaceChild as keyof StateEvents,
             {
               auto_join: false,
               suggested: false,
@@ -164,7 +165,9 @@ export function AddExistingModal({ parentId, space, requestClose }: AddExistingM
   };
 
   const handleApplyChanges = () => {
-    const selectedRooms = selected.map((rId) => getRoom(rId)).filter((room) => room !== undefined);
+    const selectedRooms = selected
+      .map((rId) => getRoom(rId))
+      .filter((room): room is Room => room !== undefined);
     applyChanges(selectedRooms).then(() => {
       if (alive()) {
         setSelected([]);
diff --git a/src/app/features/bots/BotWidgetEmbed.ts b/src/app/features/bots/BotWidgetEmbed.ts
index 7b3ed8c2..54090bde 100644
--- a/src/app/features/bots/BotWidgetEmbed.ts
+++ b/src/app/features/bots/BotWidgetEmbed.ts
@@ -264,7 +264,9 @@ export class BotWidgetEmbed {
     } catch {
       return;
     }
-    void openExternalUrl(url);
+    openExternalUrl(url).catch(() => {
+      /* fire-and-forget: log handled inside openExternalUrl */
+    });
   };
 
   public constructor(private readonly options: BotWidgetEmbedOptions) {
diff --git a/src/app/features/call/CallMemberCard.tsx b/src/app/features/call/CallMemberCard.tsx
index 46903f80..1c3680f5 100644
--- a/src/app/features/call/CallMemberCard.tsx
+++ b/src/app/features/call/CallMemberCard.tsx
@@ -47,7 +47,7 @@ export function CallMemberCard({ member }: CallMemberCardProps) {
       className={css.CallMemberCard}
       variant="SurfaceVariant"
       radii="500"
-      onClick={(evt: any) =>
+      onClick={(evt: React.MouseEvent<HTMLButtonElement>) =>
         openUserProfile(
           room.roomId,
           undefined,
diff --git a/src/app/features/common-settings/developer-tools/SendRoomEvent.tsx b/src/app/features/common-settings/developer-tools/SendRoomEvent.tsx
index 729690ec..d86224c6 100644
--- a/src/app/features/common-settings/developer-tools/SendRoomEvent.tsx
+++ b/src/app/features/common-settings/developer-tools/SendRoomEvent.tsx
@@ -1,6 +1,7 @@
 import React, { useCallback, useRef, useState, FormEventHandler, useEffect } from 'react';
 import { useTranslation } from 'react-i18next';
 import { MatrixError } from 'matrix-js-sdk';
+import type { StateEvents, TimelineEvents } from 'matrix-js-sdk';
 import {
   Box,
   Chip,
@@ -53,9 +54,18 @@ export function SendRoomEvent({ type, stateKey, requestClose }: SendRoomEventPro
     useCallback(
       (evtType, evtStateKey, evtContent) => {
         if (typeof evtStateKey === 'string') {
-          return mx.sendStateEvent(room.roomId, evtType as any, evtContent, evtStateKey);
+          return mx.sendStateEvent(
+            room.roomId,
+            evtType as keyof StateEvents,
+            evtContent as StateEvents[keyof StateEvents],
+            evtStateKey
+          );
         }
-        return mx.sendEvent(room.roomId, evtType as any, evtContent);
+        return mx.sendEvent(
+          room.roomId,
+          evtType as keyof TimelineEvents,
+          evtContent as TimelineEvents[keyof TimelineEvents]
+        );
       },
       [mx, room]
     )
diff --git a/src/app/features/common-settings/developer-tools/StateEventEditor.tsx b/src/app/features/common-settings/developer-tools/StateEventEditor.tsx
index 5ce9341c..5bdeb970 100644
--- a/src/app/features/common-settings/developer-tools/StateEventEditor.tsx
+++ b/src/app/features/common-settings/developer-tools/StateEventEditor.tsx
@@ -15,6 +15,7 @@ import {
 } from 'folds';
 import { useTranslation } from 'react-i18next';
 import { MatrixError } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { Page, PageHeader } from '../../../components/page';
 import { SequenceCard } from '../../../components/sequence-card';
 import { TextViewerContent } from '../../../components/text-viewer';
@@ -61,7 +62,13 @@ function StateEventEdit({ type, stateKey, content, requestClose }: StateEventEdi
 
   const [submitState, submit] = useAsyncCallback<object, MatrixError, [object]>(
     useCallback(
-      (c) => mx.sendStateEvent(room.roomId, type as any, c, stateKey),
+      (c) =>
+        mx.sendStateEvent(
+          room.roomId,
+          type as keyof StateEvents,
+          c as StateEvents[keyof StateEvents],
+          stateKey
+        ),
       [mx, room, type, stateKey]
     )
   );
diff --git a/src/app/features/common-settings/emojis-stickers/RoomPacks.tsx b/src/app/features/common-settings/emojis-stickers/RoomPacks.tsx
index 0979cc1a..e36d3484 100644
--- a/src/app/features/common-settings/emojis-stickers/RoomPacks.tsx
+++ b/src/app/features/common-settings/emojis-stickers/RoomPacks.tsx
@@ -18,6 +18,7 @@ import {
 } from 'folds';
 import { useTranslation } from 'react-i18next';
 import { MatrixError } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { SequenceCard } from '../../../components/sequence-card';
 import {
   ImagePack,
@@ -59,7 +60,12 @@ function CreatePackTile({ packs, roomId }: CreatePackTileProps) {
             display_name: name,
           },
         };
-        await mx.sendStateEvent(roomId, StateEvent.PoniesRoomEmotes as any, content, stateKey);
+        await mx.sendStateEvent(
+          roomId,
+          StateEvent.PoniesRoomEmotes as keyof StateEvents,
+          content as StateEvents[keyof StateEvents],
+          stateKey
+        );
       },
       [mx, roomId]
     )
@@ -164,7 +170,12 @@ export function RoomPacks({ onViewPack }: RoomPacksProps) {
       for (let i = 0; i < removedPacks.length; i += 1) {
         const addr = removedPacks[i];
         // eslint-disable-next-line no-await-in-loop
-        await mx.sendStateEvent(room.roomId, StateEvent.PoniesRoomEmotes as any, {}, addr.stateKey);
+        await mx.sendStateEvent(
+          room.roomId,
+          StateEvent.PoniesRoomEmotes as keyof StateEvents,
+          {} as StateEvents[keyof StateEvents],
+          addr.stateKey
+        );
       }
     }, [mx, room, removedPacks])
   );
diff --git a/src/app/features/common-settings/general/RoomAddress.tsx b/src/app/features/common-settings/general/RoomAddress.tsx
index 275a6ff2..bcae00c3 100644
--- a/src/app/features/common-settings/general/RoomAddress.tsx
+++ b/src/app/features/common-settings/general/RoomAddress.tsx
@@ -65,6 +65,9 @@ export function RoomPublishedAddresses({ permissions }: RoomPublishedAddressesPr
       <SettingTile
         title={t('RoomSettings.published_addresses')}
         description={
+          // Static i18n string from the in-repo locale bundle — only `<b>`
+          // markup, no user-controlled input. Safe.
+          // eslint-disable-next-line react/no-danger
           <span dangerouslySetInnerHTML={{ __html: t('RoomSettings.published_addresses_desc') }} />
         }
       />
diff --git a/src/app/features/common-settings/general/RoomEncryption.tsx b/src/app/features/common-settings/general/RoomEncryption.tsx
index 425a47d7..fde639b7 100644
--- a/src/app/features/common-settings/general/RoomEncryption.tsx
+++ b/src/app/features/common-settings/general/RoomEncryption.tsx
@@ -17,6 +17,7 @@ import {
 } from 'folds';
 import React, { useCallback, useState } from 'react';
 import { MatrixError } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import FocusTrap from 'focus-trap-react';
 import { useTranslation } from 'react-i18next';
 import { SequenceCard } from '../../../components/sequence-card';
@@ -48,7 +49,7 @@ export function RoomEncryption({ permissions }: RoomEncryptionProps) {
 
   const [enableState, enable] = useAsyncCallback(
     useCallback(async () => {
-      await mx.sendStateEvent(room.roomId, StateEvent.RoomEncryption as any, {
+      await mx.sendStateEvent(room.roomId, StateEvent.RoomEncryption as keyof StateEvents, {
         algorithm: ROOM_ENC_ALGO,
       });
     }, [mx, room.roomId])
diff --git a/src/app/features/common-settings/general/RoomHistoryVisibility.tsx b/src/app/features/common-settings/general/RoomHistoryVisibility.tsx
index 4c9ccf9b..4af93e4e 100644
--- a/src/app/features/common-settings/general/RoomHistoryVisibility.tsx
+++ b/src/app/features/common-settings/general/RoomHistoryVisibility.tsx
@@ -13,6 +13,7 @@ import {
   Text,
 } from 'folds';
 import { HistoryVisibility, MatrixError } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { RoomHistoryVisibilityEventContent } from 'matrix-js-sdk/lib/types';
 import FocusTrap from 'focus-trap-react';
 import { useTranslation } from 'react-i18next';
@@ -80,7 +81,11 @@ export function RoomHistoryVisibility({ permissions }: RoomHistoryVisibilityProp
         const content: RoomHistoryVisibilityEventContent = {
           history_visibility: visibility,
         };
-        await mx.sendStateEvent(room.roomId, StateEvent.RoomHistoryVisibility as any, content);
+        await mx.sendStateEvent(
+          room.roomId,
+          StateEvent.RoomHistoryVisibility as keyof StateEvents,
+          content
+        );
       },
       [mx, room.roomId]
     )
diff --git a/src/app/features/common-settings/general/RoomJoinRules.tsx b/src/app/features/common-settings/general/RoomJoinRules.tsx
index 842e7570..6279822e 100644
--- a/src/app/features/common-settings/general/RoomJoinRules.tsx
+++ b/src/app/features/common-settings/general/RoomJoinRules.tsx
@@ -2,6 +2,7 @@ import React, { useCallback, useMemo } from 'react';
 import { color, Text } from 'folds';
 import { useTranslation } from 'react-i18next';
 import { JoinRule, MatrixError, RestrictedAllowType } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { RoomJoinRulesEventContent } from 'matrix-js-sdk/lib/types';
 import { useAtomValue } from 'jotai';
 import {
@@ -88,7 +89,7 @@ export function RoomJoinRules({ permissions }: RoomJoinRulesProps) {
 
           const parents = getStateEvents(room, StateEvent.SpaceParent)
             .map((event) => event.getStateKey())
-            .filter((parentId) => typeof parentId === 'string')
+            .filter((parentId): parentId is string => typeof parentId === 'string')
             .filter((parentId) => roomParents?.has(parentId));
 
           if (parents.length === 0 && space && roomParents) {
@@ -113,7 +114,7 @@ export function RoomJoinRules({ permissions }: RoomJoinRulesProps) {
           join_rule: joinRule as JoinRule,
         };
         if (allow.length > 0) c.allow = allow;
-        await mx.sendStateEvent(room.roomId, StateEvent.RoomJoinRules as any, c);
+        await mx.sendStateEvent(room.roomId, StateEvent.RoomJoinRules as keyof StateEvents, c);
       },
       [mx, room, space, subspaces, roomIdToParents]
     )
diff --git a/src/app/features/common-settings/general/RoomProfile.tsx b/src/app/features/common-settings/general/RoomProfile.tsx
index 5382218d..bade282a 100644
--- a/src/app/features/common-settings/general/RoomProfile.tsx
+++ b/src/app/features/common-settings/general/RoomProfile.tsx
@@ -16,6 +16,7 @@ import { useTranslation } from 'react-i18next';
 import Linkify from 'linkify-react';
 import classNames from 'classnames';
 import { JoinRule, MatrixError } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { SequenceCard } from '../../../components/sequence-card';
 import { SequenceCardStyle } from '../../room-settings/styles.css';
 import { useRoom } from '../../../hooks/useRoom';
@@ -94,15 +95,19 @@ export function RoomProfileEdit({
     useCallback(
       async (roomAvatarMxc?: string | null, roomName?: string, roomTopic?: string) => {
         if (roomAvatarMxc !== undefined) {
-          await mx.sendStateEvent(room.roomId, StateEvent.RoomAvatar as any, {
+          await mx.sendStateEvent(room.roomId, StateEvent.RoomAvatar as keyof StateEvents, {
             url: roomAvatarMxc,
           });
         }
         if (roomName !== undefined) {
-          await mx.sendStateEvent(room.roomId, StateEvent.RoomName as any, { name: roomName });
+          await mx.sendStateEvent(room.roomId, StateEvent.RoomName as keyof StateEvents, {
+            name: roomName,
+          });
         }
         if (roomTopic !== undefined) {
-          await mx.sendStateEvent(room.roomId, StateEvent.RoomTopic as any, { topic: roomTopic });
+          await mx.sendStateEvent(room.roomId, StateEvent.RoomTopic as keyof StateEvents, {
+            topic: roomTopic,
+          });
         }
       },
       [mx, room.roomId]
diff --git a/src/app/features/common-settings/permissions/PermissionGroups.tsx b/src/app/features/common-settings/permissions/PermissionGroups.tsx
index daa3c41d..f173b595 100644
--- a/src/app/features/common-settings/permissions/PermissionGroups.tsx
+++ b/src/app/features/common-settings/permissions/PermissionGroups.tsx
@@ -3,6 +3,7 @@ import React, { useCallback, useEffect, useMemo, useState } from 'react';
 import { Badge, Box, Button, Chip, config, Icon, Icons, Menu, Spinner, Text } from 'folds';
 import { useTranslation } from 'react-i18next';
 import produce from 'immer';
+import type { StateEvents } from 'matrix-js-sdk';
 import { SequenceCard } from '../../../components/sequence-card';
 import { SequenceCardStyle } from '../styles.css';
 import { SettingTile } from '../../../components/setting-tile';
@@ -87,7 +88,11 @@ export function PermissionGroups({
 
         return draftPowerLevels;
       });
-      await mx.sendStateEvent(room.roomId, StateEvent.RoomPowerLevels as any, editedPowerLevels);
+      await mx.sendStateEvent(
+        room.roomId,
+        StateEvent.RoomPowerLevels as keyof StateEvents,
+        editedPowerLevels
+      );
     }, [mx, room, powerLevels, permissionUpdate, permissionGroups])
   );
 
diff --git a/src/app/features/common-settings/permissions/PowersEditor.tsx b/src/app/features/common-settings/permissions/PowersEditor.tsx
index b45da7d1..c94a0f7b 100644
--- a/src/app/features/common-settings/permissions/PowersEditor.tsx
+++ b/src/app/features/common-settings/permissions/PowersEditor.tsx
@@ -21,6 +21,7 @@ import {
 import { HexColorPicker } from 'react-colorful';
 import { useTranslation } from 'react-i18next';
 import { useAtomValue } from 'jotai';
+import type { StateEvents } from 'matrix-js-sdk';
 import { Page, PageContent, PageHeader } from '../../../components/page';
 import { IPowerLevels } from '../../../hooks/usePowerLevels';
 import { SequenceCard } from '../../../components/sequence-card';
@@ -336,7 +337,7 @@ export function PowersEditor({ powerLevels, requestClose }: PowersEditorProps) {
       deleted.forEach((power) => {
         delete content[power];
       });
-      await mx.sendStateEvent(room.roomId, StateEvent.PowerLevelTags as any, content);
+      await mx.sendStateEvent(room.roomId, StateEvent.PowerLevelTags as keyof StateEvents, content);
     }, [mx, room, powerLevelTags, editedPowerTags, deleted])
   );
 
diff --git a/src/app/features/lobby/HierarchyItemMenu.tsx b/src/app/features/lobby/HierarchyItemMenu.tsx
index c6aff741..a76f6aa2 100644
--- a/src/app/features/lobby/HierarchyItemMenu.tsx
+++ b/src/app/features/lobby/HierarchyItemMenu.tsx
@@ -15,6 +15,7 @@ import {
   Spinner,
   toRem,
 } from 'folds';
+import type { StateEvents } from 'matrix-js-sdk';
 import { HierarchyItem } from '../../hooks/useSpaceHierarchy';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { MSpaceChildContent, StateEvent } from '../../../types/matrix/room';
@@ -48,7 +49,12 @@ function SuggestMenuItem({
   const [toggleState, handleToggleSuggested] = useAsyncCallback(
     useCallback(() => {
       const newContent: MSpaceChildContent = { ...content, suggested: !content.suggested };
-      return mx.sendStateEvent(parentId, StateEvent.SpaceChild as any, newContent, roomId);
+      return mx.sendStateEvent(
+        parentId,
+        StateEvent.SpaceChild as keyof StateEvents,
+        newContent,
+        roomId
+      );
     }, [mx, parentId, roomId, content])
   );
 
@@ -85,7 +91,7 @@ function RemoveMenuItem({
 
   const [removeState, handleRemove] = useAsyncCallback(
     useCallback(
-      () => mx.sendStateEvent(parentId, StateEvent.SpaceChild as any, {}, roomId),
+      () => mx.sendStateEvent(parentId, StateEvent.SpaceChild as keyof StateEvents, {}, roomId),
       [mx, parentId, roomId]
     )
   );
diff --git a/src/app/features/lobby/Lobby.tsx b/src/app/features/lobby/Lobby.tsx
index cd212d72..1ea6f542 100644
--- a/src/app/features/lobby/Lobby.tsx
+++ b/src/app/features/lobby/Lobby.tsx
@@ -4,6 +4,7 @@ import { useVirtualizer } from '@tanstack/react-virtual';
 import { useAtom, useAtomValue } from 'jotai';
 import { useNavigate } from 'react-router-dom';
 import { JoinRule, RestrictedAllowType, Room } from 'matrix-js-sdk';
+import type { AccountDataEvents, StateEvents } from 'matrix-js-sdk';
 import { RoomJoinRulesEventContent } from 'matrix-js-sdk/lib/types';
 import { IHierarchyRoom } from 'matrix-js-sdk/lib/@types/spaces';
 import produce from 'immer';
@@ -273,7 +274,7 @@ export function Lobby() {
             if (!reorder.item.parentId) return;
             await mx.sendStateEvent(
               reorder.item.parentId,
-              StateEvent.SpaceChild as any,
+              StateEvent.SpaceChild as keyof StateEvents,
               { ...reorder.item.content, order: reorder.orderKey },
               reorder.item.roomId
             );
@@ -298,7 +299,12 @@ export function Lobby() {
 
         // remove from current space
         if (item.parentId !== containerParentId) {
-          mx.sendStateEvent(item.parentId, StateEvent.SpaceChild as any, {}, item.roomId);
+          mx.sendStateEvent(
+            item.parentId,
+            StateEvent.SpaceChild as keyof StateEvents,
+            {},
+            item.roomId
+          );
         }
 
         if (
@@ -318,7 +324,7 @@ export function Lobby() {
               joinRuleContent.allow?.filter((allowRule) => allowRule.room_id !== item.parentId) ??
               [];
             allow.push({ type: RestrictedAllowType.RoomMembership, room_id: containerParentId });
-            mx.sendStateEvent(itemRoom.roomId, StateEvent.RoomJoinRules as any, {
+            mx.sendStateEvent(itemRoom.roomId, StateEvent.RoomJoinRules as keyof StateEvents, {
               ...joinRuleContent,
               allow,
             });
@@ -360,7 +366,7 @@ export function Lobby() {
           await rateLimitedActions(reorders, async (reorder) => {
             await mx.sendStateEvent(
               containerParentId,
-              StateEvent.SpaceChild as any,
+              StateEvent.SpaceChild as keyof StateEvents,
               { ...reorder.item.content, order: reorder.orderKey },
               reorder.item.roomId
             );
@@ -422,7 +428,10 @@ export function Lobby() {
         newItems.push(rId);
       }
       const newSpacesContent = makeVojoSpacesContent(mx, newItems);
-      mx.setAccountData(AccountDataEvent.VojoSpaces as any, newSpacesContent as any);
+      mx.setAccountData(
+        AccountDataEvent.VojoSpaces as keyof AccountDataEvents,
+        newSpacesContent as AccountDataEvents[keyof AccountDataEvents]
+      );
     },
     [mx, sidebarItems, sidebarSpaces]
   );
diff --git a/src/app/features/lobby/SpaceItem.tsx b/src/app/features/lobby/SpaceItem.tsx
index a66cb1f3..a2114b78 100644
--- a/src/app/features/lobby/SpaceItem.tsx
+++ b/src/app/features/lobby/SpaceItem.tsx
@@ -333,7 +333,7 @@ function AddSpaceButton({ item }: { item: HierarchyItem }) {
   };
 
   const handleCreateSpace = () => {
-    openCreateSpaceModal(item.roomId as any);
+    openCreateSpaceModal(item.roomId);
     setCords(undefined);
   };
 
diff --git a/src/app/features/room/MediaViewerBody.tsx b/src/app/features/room/MediaViewerBody.tsx
index a03ac2e5..9b655be9 100644
--- a/src/app/features/room/MediaViewerBody.tsx
+++ b/src/app/features/room/MediaViewerBody.tsx
@@ -14,13 +14,13 @@
 
 import React, { MouseEventHandler, useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { Box, Icon, IconButton, Icons, Spinner, Text } from 'folds';
-import { PageHeader } from '../../components/page';
-import { ContainerColor } from '../../styles/ContainerColor.css';
 import classNames from 'classnames';
 import FileSaver from 'file-saver';
 import { MatrixEvent, MatrixEventEvent, MsgType, RoomEvent } from 'matrix-js-sdk';
 import { useTranslation } from 'react-i18next';
 import { EncryptedAttachmentInfo } from 'browser-encrypt-attachment';
+import { PageHeader } from '../../components/page';
+import { ContainerColor } from '../../styles/ContainerColor.css';
 import { MediaViewerEntry } from '../../state/mediaViewer';
 import { useOpenMediaViewer } from '../../state/hooks/mediaViewer';
 import { AsyncStatus, useAsyncCallback } from '../../hooks/useAsyncCallback';
@@ -28,11 +28,7 @@ import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { useMediaAuthentication } from '../../hooks/useMediaAuthentication';
 import { useRoom } from '../../hooks/useRoom';
 import { useZoom } from '../../hooks/useZoom';
-import {
-  decryptFile,
-  downloadEncryptedMedia,
-  mxcUrlToHttp,
-} from '../../utils/matrix';
+import { decryptFile, downloadEncryptedMedia, mxcUrlToHttp } from '../../utils/matrix';
 import { FALLBACK_MIMETYPE } from '../../utils/mimeTypes';
 import {
   IImageContent,
@@ -74,7 +70,7 @@ function eventToEntry(roomId: string, ev: MatrixEvent): MediaViewerEntry | null
   if (!content) return null;
   const eventId = ev.getId();
   if (!eventId) return null;
-  const file = content.file;
+  const { file } = content;
   const url = file?.url ?? content.url;
   if (!url) return null;
   const encInfo: EncryptedAttachmentInfo | undefined = file
@@ -182,21 +178,18 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
     setMaxZoom(Math.min(ZOOM_CEILING_HARD_CAP, computed));
   }, []);
 
-  const clampPan = useCallback(
-    (raw: { x: number; y: number }, currentZoom: number) => {
-      const stage = stageRef.current;
-      const img = imgRef.current;
-      if (!stage || !img) return raw;
-      const stageRect = stage.getBoundingClientRect();
-      const maxX = Math.max(0, (img.offsetWidth * currentZoom - stageRect.width) / 2);
-      const maxY = Math.max(0, (img.offsetHeight * currentZoom - stageRect.height) / 2);
-      return {
-        x: Math.max(-maxX, Math.min(maxX, raw.x)),
-        y: Math.max(-maxY, Math.min(maxY, raw.y)),
-      };
-    },
-    []
-  );
+  const clampPan = useCallback((raw: { x: number; y: number }, currentZoom: number) => {
+    const stage = stageRef.current;
+    const img = imgRef.current;
+    if (!stage || !img) return raw;
+    const stageRect = stage.getBoundingClientRect();
+    const maxX = Math.max(0, (img.offsetWidth * currentZoom - stageRect.width) / 2);
+    const maxY = Math.max(0, (img.offsetHeight * currentZoom - stageRect.height) / 2);
+    return {
+      x: Math.max(-maxX, Math.min(maxX, raw.x)),
+      y: Math.max(-maxY, Math.min(maxY, raw.y)),
+    };
+  }, []);
 
   // Anchor-aware zoom math (image-local point under anchor stays
   // under the anchor after zoom change) is inlined in the pinch
@@ -279,13 +272,14 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
   //      `lastBlobUrlRef.current`", the unmount cleanup is
   //      unambiguous.
   const lastBlobUrlRef = useRef<string | null>(null);
+  const { url: entryUrl, encInfo: entryEncInfo, mimeType: entryMimeType } = entry;
   const [srcState, loadSrc] = useAsyncCallback(
     useCallback(async () => {
-      const mediaUrl = mxcUrlToHttp(mx, entry.url, useAuthentication);
+      const mediaUrl = mxcUrlToHttp(mx, entryUrl, useAuthentication);
       if (!mediaUrl) throw new Error('Invalid media URL');
-      if (entry.encInfo) {
+      if (entryEncInfo) {
         const fileContent = await downloadEncryptedMedia(mediaUrl, (encBuf) =>
-          decryptFile(encBuf, entry.mimeType ?? FALLBACK_MIMETYPE, entry.encInfo!)
+          decryptFile(encBuf, entryMimeType ?? FALLBACK_MIMETYPE, entryEncInfo)
         );
         const blob = URL.createObjectURL(fileContent);
         if (lastBlobUrlRef.current && lastBlobUrlRef.current !== blob) {
@@ -295,7 +289,7 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
         return blob;
       }
       return mediaUrl;
-    }, [mx, entry.url, entry.encInfo, entry.mimeType, useAuthentication])
+    }, [mx, entryUrl, entryEncInfo, entryMimeType, useAuthentication])
   );
 
   useEffect(() => {
@@ -375,6 +369,7 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
     return entries;
     // `timelineVersion` is the actual refresh trigger; `entry.eventId`
     // is intentionally NOT a dep — stepping doesn't change the set.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [room, timelineVersion]);
 
   const currentIndex = useMemo(
@@ -406,9 +401,7 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
       const target = e.target as HTMLElement | null;
       if (
         target &&
-        (target.tagName === 'INPUT' ||
-          target.tagName === 'TEXTAREA' ||
-          target.isContentEditable)
+        (target.tagName === 'INPUT' || target.tagName === 'TEXTAREA' || target.isContentEditable)
       ) {
         return;
       }
@@ -622,10 +615,7 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
         const pts = Array.from(pointerCacheRef.current.values());
         const dist = distanceBetween(pts[0], pts[1]);
         const ratio = dist / ps.initialDistance;
-        const nextZoom = Math.max(
-          MIN_ZOOM,
-          Math.min(maxZoomRef.current, ps.initialZoom * ratio)
-        );
+        const nextZoom = Math.max(MIN_ZOOM, Math.min(maxZoomRef.current, ps.initialZoom * ratio));
         // Anchor-aware: hold `anchorImage*` (image-local point
         // captured at pinch start) under the moving midpoint.
         const midClientX = (pts[0].x + pts[1].x) / 2;
@@ -661,8 +651,7 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
         }
         if (s.claimed !== 'swipe') return;
         if (e.cancelable) e.preventDefault();
-        const blocked =
-          (dx > 0 && !canPrevRef.current) || (dx < 0 && !canNextRef.current);
+        const blocked = (dx > 0 && !canPrevRef.current) || (dx < 0 && !canNextRef.current);
         setSwipeOffset(blocked ? dx / 3 : dx);
         return;
       }
@@ -731,10 +720,14 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
     const onWheel = (e: WheelEvent) => {
       if (entryKindRef.current !== 'image') return;
       e.preventDefault();
-      const dyPx =
-        e.deltaMode === 1 ? e.deltaY * 16 // line mode → ~16px / line
-        : e.deltaMode === 2 ? e.deltaY * stageEl.clientHeight // page mode
-        : e.deltaY;
+      let dyPx: number;
+      if (e.deltaMode === 1) {
+        dyPx = e.deltaY * 16; // line mode → ~16px / line
+      } else if (e.deltaMode === 2) {
+        dyPx = e.deltaY * stageEl.clientHeight; // page mode
+      } else {
+        dyPx = e.deltaY;
+      }
       const factor = Math.exp(-dyPx * 0.0025);
       const oldZoom = zoomRef.current;
       const nextZoomRaw = oldZoom * factor;
@@ -802,7 +795,8 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
   const transform = isReady
     ? `translate3d(${swipeOffset + pan.x}px, ${pan.y}px, 0) scale(${zoom})`
     : undefined;
-  const imageTransition = swipeOffset === 0 ? 'transform 200ms cubic-bezier(0.32, 0.72, 0, 1)' : 'none';
+  const imageTransition =
+    swipeOffset === 0 ? 'transform 200ms cubic-bezier(0.32, 0.72, 0, 1)' : 'none';
 
   return (
     <div className={css.root}>
@@ -863,9 +857,7 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
           >
             <Icon size="100" src={Icons.Download} />
           </IconButton>
-          {entry.kind === 'image' && (
-            <div className={css.headerSeparator} aria-hidden="true" />
-          )}
+          {entry.kind === 'image' && <div className={css.headerSeparator} aria-hidden="true" />}
           <IconButton
             variant="Background"
             fill="None"
@@ -881,6 +873,9 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
 
       <div className={css.stage} ref={stageRef}>
         {isReady && effectiveSrc && entry.kind === 'image' && (
+          // `onMouseDown` drives drag-pan when the image is zoomed in.
+          // Keyboard pan is wired separately at the stage level.
+          // eslint-disable-next-line jsx-a11y/no-noninteractive-element-interactions
           <img
             ref={imgRef}
             src={effectiveSrc}
@@ -965,7 +960,6 @@ export function MediaViewerBody({ entry, requestClose }: MediaViewerBodyProps) {
           </>
         )}
       </div>
-
     </div>
   );
 }
diff --git a/src/app/features/room/RoomInput.tsx b/src/app/features/room/RoomInput.tsx
index 9c046abd..f8fbe427 100644
--- a/src/app/features/room/RoomInput.tsx
+++ b/src/app/features/room/RoomInput.tsx
@@ -13,6 +13,7 @@ import { useAtom, useAtomValue } from 'jotai';
 import { isKeyHotkey } from 'is-hotkey';
 import { useTranslation } from 'react-i18next';
 import { EventType, IContent, MsgType, RelationType, Room } from 'matrix-js-sdk';
+import type { RoomMessageEventContent } from 'matrix-js-sdk/lib/types';
 import { ReactEditor } from 'slate-react';
 import { Transforms, Editor } from 'slate';
 import {
@@ -149,12 +150,7 @@ const COMPOSER_PLACEHOLDER_KEYS = [
 // no fills.
 const StreamComposerIcons = {
   Plus: () => (
-    <path
-      d="M12 5v14M5 12h14"
-      stroke="currentColor"
-      strokeWidth="1.8"
-      strokeLinecap="round"
-    />
+    <path d="M12 5v14M5 12h14" stroke="currentColor" strokeWidth="1.8" strokeLinecap="round" />
   ),
   Smile: () => (
     <>
@@ -238,9 +234,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
     const replyUsernameColor = isOneOnOne ? colorMXID(replyUserID ?? '') : replyPowerColor;
 
     const [uploadBoard, setUploadBoard] = useState(true);
-    const [selectedFiles, setSelectedFiles] = useAtom(
-      roomIdToUploadItemsAtomFamily(inputDraftKey)
-    );
+    const [selectedFiles, setSelectedFiles] = useAtom(roomIdToUploadItemsAtomFamily(inputDraftKey));
     const uploadFamilyObserverAtom = createUploadFamilyObserverAtom(
       roomUploadAtomFamily,
       selectedFiles.map((f) => f.file)
@@ -374,7 +368,9 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
       });
       handleCancelUpload(uploads);
       const contents = fulfilledPromiseSettledResult(await Promise.allSettled(contentsPromises));
-      contents.forEach((content) => mx.sendMessage(roomId, threadId ?? null, content as any));
+      contents.forEach((content) =>
+        mx.sendMessage(roomId, threadId ?? null, content as RoomMessageEventContent)
+      );
     };
 
     const submit = useCallback(() => {
@@ -453,7 +449,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
           content['m.relates_to'].is_falling_back = false;
         }
       }
-      mx.sendMessage(roomId, threadId ?? null, content as any);
+      mx.sendMessage(roomId, threadId ?? null, content as RoomMessageEventContent);
       resetEditor(editor);
       resetEditorHistory(editor);
       setReplyDraft(undefined);
@@ -634,8 +630,9 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
     const placeholderKey = useMemo(() => {
       const idx = new Date().getHours() % COMPOSER_PLACEHOLDER_KEYS.length;
       return COMPOSER_PLACEHOLDER_KEYS[idx];
-      // roomId and threadId are intentional re-roll triggers; the
-      // exhaustive-deps lint is happy with them too.
+      // roomId and threadId are intentional re-roll triggers (re-memoize on
+      // chat/thread navigation), not values read inside the body.
+      // eslint-disable-next-line react-hooks/exhaustive-deps
     }, [roomId, threadId]);
 
     return (
diff --git a/src/app/features/room/RoomTimeline.tsx b/src/app/features/room/RoomTimeline.tsx
index aaa79cc5..f9c2c9a1 100644
--- a/src/app/features/room/RoomTimeline.tsx
+++ b/src/app/features/room/RoomTimeline.tsx
@@ -27,17 +27,7 @@ import { Editor } from 'slate';
 import { DEFAULT_EXPIRE_DURATION, SessionMembershipData } from 'matrix-js-sdk/lib/matrixrtc';
 import to from 'await-to-js';
 import { useAtomValue, useSetAtom } from 'jotai';
-import {
-  Box,
-  Chip,
-  Icon,
-  Icons,
-  Scroll,
-  Text,
-  as,
-  config,
-  toRem,
-} from 'folds';
+import { Box, Chip, Icon, Icons, Scroll, Text, as, config, toRem } from 'folds';
 import { isKeyHotkey } from 'is-hotkey';
 import { Opts as LinkifyOpts } from 'linkifyjs';
 import { useTranslation } from 'react-i18next';
@@ -447,7 +437,7 @@ const getEmptyTimeline = () => ({
 });
 
 const getRoomUnreadInfo = (room: Room, scrollTo = false) => {
-  const readUptoEventId = room.getEventReadUpTo(room.client.getUserId() ?? '');
+  const readUptoEventId = room.getEventReadUpTo(room.client.getSafeUserId());
   if (!readUptoEventId) return undefined;
   const evtTimeline = getEventTimeline(room, readUptoEventId);
   const latestTimeline = evtTimeline && getFirstLinkedTimeline(evtTimeline, Direction.Forward);
@@ -794,7 +784,10 @@ export function RoomTimeline({
             // Check if the document is in focus (user is actively viewing the app),
             // and either there are no unread messages or the latest message is from the current user.
             // If either condition is met, trigger the markAsRead function to send a read receipt.
-            requestAnimationFrame(() => markAsRead(mx, mEvt.getRoomId()!, hideActivity));
+            const evtRoomId = mEvt.getRoomId();
+            if (evtRoomId) {
+              requestAnimationFrame(() => markAsRead(mx, evtRoomId, hideActivity));
+            }
           }
 
           if (!document.hasFocus() && !unreadInfo) {
@@ -1308,25 +1301,32 @@ export function RoomTimeline({
     // Per-slot ordered list of sessions. Newest session is `last(sessions)`;
     // earlier entries are closed (count returned to 0).
     const slotSessions = new Map<string, CallScan[]>();
+    // Hot data-pipeline path: nested for-of with early `continue` is the
+    // clearest expression of the state-machine. Array iteration helpers would
+    // require restructuring the dual-key membership ledger.
+    /* eslint-disable no-restricted-syntax, no-continue */
     for (const tl of timeline.linkedTimelines) {
       const events = tl.getEvents();
       for (const ev of events) {
         if (ev.getType() !== StateEvent.GroupCallMemberPrefix) continue;
         const content = ev.getContent<SessionMembershipData>();
         const prevContent = ev.getPrevContent() as Partial<SessionMembershipData>;
-        const slotId =
-          typeof content.call_id === 'string'
-            ? content.call_id
-            : typeof prevContent.call_id === 'string'
-              ? prevContent.call_id
-              : null;
+        let slotId: string | null = null;
+        if (typeof content.call_id === 'string') {
+          slotId = content.call_id;
+        } else if (typeof prevContent.call_id === 'string') {
+          slotId = prevContent.call_id;
+        }
         if (slotId == null) continue;
+        // `anchorEventId` is the React key for the merged call bubble; an
+        // empty fallback would collide across multiple eventless rows.
+        const evId = ev.getId();
+        if (!evId) continue;
         const ts = ev.getTs();
         const isJoin = !!content.application;
         const wasPreviouslyJoined = !!prevContent.application;
         const sender = ev.getSender() ?? '';
         const stateKey = ev.getStateKey() ?? '';
-        const evId = ev.getId() ?? '';
 
         let sessions = slotSessions.get(slotId);
         if (!sessions) {
@@ -1407,6 +1407,7 @@ export function RoomTimeline({
         }
       }
     }
+    /* eslint-enable no-restricted-syntax, no-continue */
     const now = Date.now();
     // Consecutive unsuccessful sessions from the same caller within this
     // window collapse into one bubble (WhatsApp/iOS Recents-style anti-spam).
@@ -1432,13 +1433,15 @@ export function RoomTimeline({
       lastEndTs: number;
     };
     const anchors = new Map<string, CallAggregate>();
+    // Second pass: collapse same-sender unanswered scans into merge units.
+    // Same justification as the upstream loop — pipeline expression with
+    // early `continue` is clearer than reduce+filter chains.
+    /* eslint-disable no-restricted-syntax, no-continue */
     for (const sessions of slotSessions.values()) {
       const units: DisplayUnit[] = [];
       for (const scan of sessions) {
         if (!scan.everJoined && scan.participants.size === 0) continue;
-        const ongoing = Array.from(scan.joinedAbsoluteExpiries.values()).some(
-          (exp) => exp > now
-        );
+        const ongoing = Array.from(scan.joinedAbsoluteExpiries.values()).some((exp) => exp > now);
         const wasAnswered = scan.connectedAt !== null || scan.participants.size >= 2;
         const display: SessionDisplay = { scan, ongoing, wasAnswered };
         const mergeable = !ongoing && !wasAnswered;
@@ -1464,8 +1467,8 @@ export function RoomTimeline({
       }
       for (const unit of units) {
         const { scan, ongoing, wasAnswered } = unit.anchor;
-        const conversationStart = wasAnswered ? (scan.connectedAt ?? scan.startTs) : null;
-        const conversationEnd = wasAnswered && !ongoing ? (scan.endedAt ?? scan.endTs) : null;
+        const conversationStart = wasAnswered ? scan.connectedAt ?? scan.startTs : null;
+        const conversationEnd = wasAnswered && !ongoing ? scan.endedAt ?? scan.endTs : null;
         anchors.set(scan.anchorEventId, {
           callId: scan.slotId,
           startTs: scan.startTs,
@@ -1480,6 +1483,7 @@ export function RoomTimeline({
         });
       }
     }
+    /* eslint-enable no-restricted-syntax, no-continue */
     return anchors;
   })();
 
@@ -1574,12 +1578,10 @@ export function RoomTimeline({
             hideThreadReplyAffordance={hideThreadReplyAffordance}
             hideMainReplyAffordance={hideMainReplyAffordance}
             threadSummary={
-              showThreadSummary ? (
-                <ThreadSummaryCard room={room} rootEvent={mEvent} />
-              ) : undefined
+              showThreadSummary ? <ThreadSummaryCard room={room} rootEvent={mEvent} /> : undefined
             }
             layout={messageLayout}
-              channelHeaderInBubble={channelHeaderInBubble}
+            channelHeaderInBubble={channelHeaderInBubble}
           >
             {mEvent.isRedacted() ? (
               <RedactedContent reason={mEvent.getUnsigned().redacted_because?.content.reason} />
@@ -1690,7 +1692,7 @@ export function RoomTimeline({
                     ) : undefined
                   }
                   layout={messageLayout}
-              channelHeaderInBubble={channelHeaderInBubble}
+                  channelHeaderInBubble={channelHeaderInBubble}
                 >
                   {(() => {
                     if (mEvent.isRedacted()) return <RedactedContent />;
@@ -1807,12 +1809,10 @@ export function RoomTimeline({
             hideThreadReplyAffordance={hideThreadReplyAffordance}
             hideMainReplyAffordance={hideMainReplyAffordance}
             threadSummary={
-              showThreadSummary ? (
-                <ThreadSummaryCard room={room} rootEvent={mEvent} />
-              ) : undefined
+              showThreadSummary ? <ThreadSummaryCard room={room} rootEvent={mEvent} /> : undefined
             }
             layout={messageLayout}
-              channelHeaderInBubble={channelHeaderInBubble}
+            channelHeaderInBubble={channelHeaderInBubble}
           >
             {mEvent.isRedacted() ? (
               <RedactedContent reason={mEvent.getUnsigned().redacted_because?.content.reason} />
@@ -2025,12 +2025,7 @@ export function RoomTimeline({
       const senderId = mEvent.getSender() ?? '';
       const senderName = getMemberDisplayName(room, senderId) || getMxIdLocalPart(senderId);
 
-      const timeJSX = (
-        <Time
-          ts={mEvent.getTs()}
-          compact
-        />
-      );
+      const timeJSX = <Time ts={mEvent.getTs()} compact />;
 
       return (
         <Event
@@ -2049,7 +2044,6 @@ export function RoomTimeline({
             railStart={streamRailStart}
             railEnd={streamRailEnd}
             layout={messageLayout}
-              channelHeaderInBubble={channelHeaderInBubble}
             iconSrc={Icons.Code}
             content={
               <Box grow="Yes" direction="Column">
@@ -2075,12 +2069,7 @@ export function RoomTimeline({
       const senderId = mEvent.getSender() ?? '';
       const senderName = getMemberDisplayName(room, senderId) || getMxIdLocalPart(senderId);
 
-      const timeJSX = (
-        <Time
-          ts={mEvent.getTs()}
-          compact
-        />
-      );
+      const timeJSX = <Time ts={mEvent.getTs()} compact />;
 
       return (
         <Event
@@ -2099,7 +2088,6 @@ export function RoomTimeline({
             railStart={streamRailStart}
             railEnd={streamRailEnd}
             layout={messageLayout}
-              channelHeaderInBubble={channelHeaderInBubble}
             iconSrc={Icons.Code}
             content={
               <Box grow="Yes" direction="Column">
@@ -2280,19 +2268,20 @@ export function RoomTimeline({
     // the rail-endpoint scan and the renderer never disagree on visibility.
     const channelsModeHidden = channelsMode && isChannelsModeHidden(room, mEvent, isBridged);
 
-    const eventJSX = channelsModeHidden || reactionOrEditEvent(mEvent)
-      ? null
-      : renderMatrixEvent(
-          mEvent.getType(),
-          typeof mEvent.getStateKey() === 'string',
-          mEventId,
-          mEvent,
-          item,
-          timelineSet,
-          collapsed,
-          streamRailStart,
-          streamRailEnd
-        );
+    const eventJSX =
+      channelsModeHidden || reactionOrEditEvent(mEvent)
+        ? null
+        : renderMatrixEvent(
+            mEvent.getType(),
+            typeof mEvent.getStateKey() === 'string',
+            mEventId,
+            mEvent,
+            item,
+            timelineSet,
+            collapsed,
+            streamRailStart,
+            streamRailEnd
+          );
     prevEvent = mEvent;
     isPrevRendered = !!eventJSX;
 
diff --git a/src/app/features/room/RoomTombstone.tsx b/src/app/features/room/RoomTombstone.tsx
index 24f0b80e..d437f811 100644
--- a/src/app/features/room/RoomTombstone.tsx
+++ b/src/app/features/room/RoomTombstone.tsx
@@ -36,7 +36,8 @@ export function RoomTombstone({ roomId, body, replacementRoomId }: RoomTombstone
         <Text size="T400">{body || 'This room has been replaced and is no longer active.'}</Text>
         {joinState.status === AsyncStatus.Error && (
           <Text style={{ color: color.Critical.Main }} size="T200">
-            {(joinState.error as any)?.message ?? 'Failed to join replacement room!'}
+            {(joinState.error as { message?: string } | undefined)?.message ??
+              'Failed to join replacement room!'}
           </Text>
         )}
       </Box>
diff --git a/src/app/features/room/RoomViewProfilePanel.tsx b/src/app/features/room/RoomViewProfilePanel.tsx
index 73da4daa..538f8413 100644
--- a/src/app/features/room/RoomViewProfilePanel.tsx
+++ b/src/app/features/room/RoomViewProfilePanel.tsx
@@ -24,10 +24,7 @@ import { config } from 'folds';
 import FocusTrap from 'focus-trap-react';
 import { useTranslation } from 'react-i18next';
 import { userRoomProfileAtom } from '../../state/userRoomProfile';
-import {
-  useCloseUserRoomProfile,
-  useOpenUserRoomProfile,
-} from '../../state/hooks/userRoomProfile';
+import { useCloseUserRoomProfile, useOpenUserRoomProfile } from '../../state/hooks/userRoomProfile';
 import { ScreenSize, useScreenSizeContext } from '../../hooks/useScreenSize';
 import { useIsOneOnOne, useRoom } from '../../hooks/useRoom';
 import { useSpaceOptionally } from '../../hooks/useSpace';
@@ -95,8 +92,7 @@ const VAUL_EASING = 'cubic-bezier(0.32, 0.72, 0, 1)';
 // which is the felt-feel the user signed off on. Release animations
 // keep the asymmetric Vaul curve in CSS where direct manipulation
 // is over and the auto-animation can take centre stage.
-const easeInOutCubic = (t: number): number =>
-  t < 0.5 ? 4 * t * t * t : 1 - Math.pow(-2 * t + 2, 3) / 2;
+const easeInOutCubic = (t: number): number => (t < 0.5 ? 4 * t * t * t : 1 - (-2 * t + 2) ** 3 / 2);
 
 type RoomViewProfilePanelProps = {
   header: ReactNode;
@@ -138,8 +134,7 @@ function MobileProfileHorseshoe({ header, children }: RoomViewProfilePanelProps)
 
   const myUserId = mx.getSafeUserId();
   const peerCandidate = isOneOnOne ? guessDmRoomUserId(room, myUserId) : undefined;
-  const headerDragPeer =
-    peerCandidate && peerCandidate !== myUserId ? peerCandidate : undefined;
+  const headerDragPeer = peerCandidate && peerCandidate !== myUserId ? peerCandidate : undefined;
   const headerDragEnabled = !!headerDragPeer;
 
   const [drag, setDrag] = useState<DragState | null>(null);
@@ -215,8 +210,7 @@ function MobileProfileHorseshoe({ header, children }: RoomViewProfilePanelProps)
   // (very rare — multiple stacked moderation alerts). In the common
   // case the rail is exactly content-sized and there is nothing to
   // scroll — `overflow: hidden` then prevents any drag-inside-drag.
-  const contentOverflows =
-    contentNaturalHeight > 0 && contentNaturalHeight > maxRailPx;
+  const contentOverflows = contentNaturalHeight > 0 && contentNaturalHeight > maxRailPx;
 
   // Measure the chat header's natural height (incl. its safe-top padding).
   // `scrollHeight` returns the content size even while the outer is
@@ -252,9 +246,7 @@ function MobileProfileHorseshoe({ header, children }: RoomViewProfilePanelProps)
   if (liveUserId) lastUserIdRef.current = liveUserId;
   const renderUserId = liveUserId ?? lastUserIdRef.current;
 
-  const renderUserAvatarMxc = renderUserId
-    ? getMemberAvatarMxc(room, renderUserId)
-    : undefined;
+  const renderUserAvatarMxc = renderUserId ? getMemberAvatarMxc(room, renderUserId) : undefined;
   const renderUserAvatarUrl =
     (renderUserAvatarMxc &&
       mxcUrlToHttp(mx, renderUserAvatarMxc, useAuthentication, 720, 720, 'scale')) ??
@@ -444,22 +436,21 @@ function MobileProfileHorseshoe({ header, children }: RoomViewProfilePanelProps)
   // The same ramp factor feeds all three properties so they always
   // appear and disappear together — no per-element timing skew that
   // could create a perceived «blip».
-  const horseshoeRamp = isDragging
-    ? easeInOutCubic(Math.min(1, expandedPx / HORSESHOE_EMERGE_PX))
-    : horseshoeActive
-    ? 1
-    : 0;
+  let horseshoeRamp: number;
+  if (isDragging) {
+    horseshoeRamp = easeInOutCubic(Math.min(1, expandedPx / HORSESHOE_EMERGE_PX));
+  } else if (horseshoeActive) {
+    horseshoeRamp = 1;
+  } else {
+    horseshoeRamp = 0;
+  }
 
   const silhouetteRadiusPx = horseshoeRamp * css.HORSESHOE_RADIUS_PX;
   const chatRadiusPx = horseshoeRamp * css.HORSESHOE_RADIUS_PX;
   const chatGapPx = horseshoeRamp * css.HORSESHOE_GAP_PX;
 
-  const panelViewportTransition = isDragging
-    ? 'none'
-    : `height ${ANIMATION_MS}ms ${VAUL_EASING}`;
-  const headerViewportTransition = isDragging
-    ? 'none'
-    : `height ${ANIMATION_MS}ms ${VAUL_EASING}`;
+  const panelViewportTransition = isDragging ? 'none' : `height ${ANIMATION_MS}ms ${VAUL_EASING}`;
+  const headerViewportTransition = isDragging ? 'none' : `height ${ANIMATION_MS}ms ${VAUL_EASING}`;
   const silhouetteTransition = isDragging
     ? 'none'
     : `border-bottom-left-radius ${ANIMATION_MS}ms ${VAUL_EASING}, border-bottom-right-radius ${ANIMATION_MS}ms ${VAUL_EASING}`;
diff --git a/src/app/features/room/ThreadDrawer.tsx b/src/app/features/room/ThreadDrawer.tsx
index 055bb9a7..fa6ff72c 100644
--- a/src/app/features/room/ThreadDrawer.tsx
+++ b/src/app/features/room/ThreadDrawer.tsx
@@ -2,19 +2,7 @@ import React, { useCallback, useEffect, useLayoutEffect, useMemo, useRef, useSta
 import { useNavigate, useParams } from 'react-router-dom';
 import { useTranslation } from 'react-i18next';
 import { useAtom, useAtomValue, useSetAtom } from 'jotai';
-import {
-  Box,
-  Button,
-  Header,
-  Icon,
-  IconButton,
-  Icons,
-  Scroll,
-  Spinner,
-  Text,
-  config,
-  toRem,
-} from 'folds';
+import { Box, Button, Header, Icon, IconButton, Icons, Scroll, Spinner, Text, config } from 'folds';
 import {
   Direction,
   EventTimeline,
@@ -59,12 +47,7 @@ import { ImageViewer } from '../../components/image-viewer';
 import { RenderMessageContent } from '../../components/RenderMessageContent';
 import { RoomInput } from './RoomInput';
 import { RoomInputPlaceholder } from './RoomInputPlaceholder';
-import {
-  EncryptedContent,
-  Message,
-  Reactions,
-  useMessageInteractionHandlers,
-} from './message';
+import { EncryptedContent, Message, Reactions, useMessageInteractionHandlers } from './message';
 import { useRoomPermissions } from '../../hooks/useRoomPermissions';
 import { useRoomCreators } from '../../hooks/useRoomCreators';
 import { usePowerLevelsContext } from '../../hooks/usePowerLevels';
@@ -76,10 +59,7 @@ import { useTheme } from '../../hooks/useTheme';
 import { useImagePackRooms } from '../../hooks/useImagePackRooms';
 import { useRoomCreatorsTag } from '../../hooks/useRoomCreatorsTag';
 import { usePowerLevelTags } from '../../hooks/usePowerLevelTags';
-import {
-  useAccessiblePowerTagColors,
-  useGetMemberPowerTag,
-} from '../../hooks/useMemberPowerTag';
+import { useAccessiblePowerTagColors, useGetMemberPowerTag } from '../../hooks/useMemberPowerTag';
 import { roomToParentsAtom } from '../../state/room/roomToParents';
 import { draftKey, roomIdToReplyDraftAtomFamily } from '../../state/room/roomInputDrafts';
 import { useSetting } from '../../state/hooks/settings';
@@ -149,12 +129,7 @@ type ThreadDrawerProps = {
 // empty). The component is intentionally light on chrome compared to
 // the full Message renderer in the timeline: M2 is MVP and rich
 // reactions / hover-menus / rail-dot inside the drawer is M9 territory.
-export function ThreadDrawer({
-  room,
-  rootId,
-  parentRoomPath,
-  variant,
-}: ThreadDrawerProps) {
+export function ThreadDrawer({ room, rootId, parentRoomPath, variant }: ThreadDrawerProps) {
   const { t } = useTranslation();
   const mx = useMatrixClient();
   const navigate = useNavigate();
@@ -172,9 +147,7 @@ export function ThreadDrawer({
   const resizableRef = useRef<HTMLDivElement>(null);
   const resizeHandleRef = useRef<HTMLDivElement>(null);
   const [savedWidth, setSavedWidth] = useAtom(threadDrawerWidthAtom);
-  const [vw, setVw] = useState<number>(
-    typeof window !== 'undefined' ? window.innerWidth : 1280
-  );
+  const [vw, setVw] = useState<number>(typeof window !== 'undefined' ? window.innerWidth : 1280);
   const [dragging, setDragging] = useState(false);
   // Live width during a drag — kept in component state so we don't
   // flush localStorage on every pointermove (hundreds of sync disk
@@ -194,8 +167,7 @@ export function ThreadDrawer({
   // Viewports too narrow for any meaningful range (max == min) hide the
   // handle entirely — leaving a non-draggable handle reads as broken UI.
   const canResize = isDesktopVariant && drawerMaxW > THREAD_DRAWER_WIDTH_MIN;
-  const atMin =
-    dragging && liveWidth !== null && liveWidth <= THREAD_DRAWER_WIDTH_MIN;
+  const atMin = dragging && liveWidth !== null && liveWidth <= THREAD_DRAWER_WIDTH_MIN;
   const atMax = dragging && liveWidth !== null && liveWidth >= drawerMaxW;
 
   // Body-style cleanup if the drag terminates without `pointerup`
@@ -375,9 +347,7 @@ export function ThreadDrawer({
   // The `RoomInput` instance below subscribes to the same atom via
   // `draftKey(roomId, threadId)` (see `roomInputDrafts.ts:34-37`) so
   // the chip surfaces inside the drawer composer.
-  const setReplyDraft = useSetAtom(
-    roomIdToReplyDraftAtomFamily(draftKey(room.roomId, rootId))
-  );
+  const setReplyDraft = useSetAtom(roomIdToReplyDraftAtomFamily(draftKey(room.roomId, rootId)));
 
   // Reply-chip click scrolls within the drawer to the matching
   // `data-message-id` row. If the target lives in the main timeline
@@ -387,9 +357,7 @@ export function ThreadDrawer({
   const handleScrollToDrawerEvent = useCallback((evtId: string) => {
     const host = scrollHostRef.current;
     if (!host) return;
-    const target = host.querySelector<HTMLElement>(
-      `[data-message-id="${evtId}"]`
-    );
+    const target = host.querySelector<HTMLElement>(`[data-message-id="${evtId}"]`);
     if (target) target.scrollIntoView({ behavior: 'smooth', block: 'center' });
   }, []);
 
@@ -598,10 +566,7 @@ export function ThreadDrawer({
           // resume back-pagination from where this fetch left off.
           // null means «no more older events» (server reached the
           // thread start), which correctly disables back-pagination.
-          written.liveTimeline.setPaginationToken(
-            result.nextBatch ?? null,
-            Direction.Backward
-          );
+          written.liveTimeline.setPaginationToken(result.nextBatch ?? null, Direction.Backward);
           setThread(written);
         }
       } catch (err) {
@@ -798,9 +763,7 @@ export function ThreadDrawer({
       subscribed.push(evt);
     });
     return () => {
-      subscribed.forEach((evt) =>
-        evt.off(MatrixEventEvent.RelationsCreated, handler)
-      );
+      subscribed.forEach((evt) => evt.off(MatrixEventEvent.RelationsCreated, handler));
     };
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [rootEvent, repliesIds]);
@@ -921,8 +884,11 @@ export function ThreadDrawer({
     host.scrollTop = host.scrollHeight;
     isAtBottomRef.current = true;
     tryMarkThreadRead();
-    // Intentional: replies array read inside is stable identity-wise
-    // because computed inline; lint disable for the false-positive.
+    // `replies[last]` is read but the array isn't a dep: the effect is
+    // keyed on `repliesCount` so it only fires when the array actually
+    // grew, and we always want to inspect the freshest replies snapshot
+    // at that moment. Listing `replies` would just refire on every render
+    // for the same growth event.
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [repliesCount, myUserId, tryMarkThreadRead]);
 
@@ -998,12 +964,9 @@ export function ThreadDrawer({
     // and `getEditedEvent` return undefined for thread replies even
     // when the SDK has fully ingested the relation.
     const eventThread = mEvent.getThread();
-    const isThreadReply =
-      mEvent.threadRootId !== undefined && mEvent.threadRootId !== eventId;
+    const isThreadReply = mEvent.threadRootId !== undefined && mEvent.threadRootId !== eventId;
     const timelineSet =
-      isThreadReply && eventThread
-        ? eventThread.timelineSet
-        : room.getUnfilteredTimelineSet();
+      isThreadReply && eventThread ? eventThread.timelineSet : room.getUnfilteredTimelineSet();
     const reactionRelations = getEventReactions(timelineSet, eventId);
     const reactionList = reactionRelations?.getSortedAnnotationsByKey();
     const hasReactions = reactionList && reactionList.length > 0;
@@ -1029,8 +992,7 @@ export function ThreadDrawer({
       // intentional quotes from auto-fallback chains.
       const wireRelatesTo = mEvent.getWireContent()['m.relates_to'];
       const isFallbackInReplyTo =
-        wireRelatesTo?.rel_type === RelationType.Thread &&
-        wireRelatesTo?.is_falling_back !== false;
+        wireRelatesTo?.rel_type === RelationType.Thread && wireRelatesTo?.is_falling_back !== false;
       const showReplyChip = !!replyEventId && !isFallbackInReplyTo;
 
       return (
@@ -1097,9 +1059,7 @@ export function ThreadDrawer({
           {(() => {
             if (mEvent.isRedacted()) {
               return (
-                <RedactedContent
-                  reason={mEvent.getUnsigned().redacted_because?.content?.reason}
-                />
+                <RedactedContent reason={mEvent.getUnsigned().redacted_because?.content?.reason} />
               );
             }
             if (eventType === MessageEvent.Sticker) {
@@ -1242,21 +1202,24 @@ export function ThreadDrawer({
             </Button>
           </div>
         )}
-        {thread && !coldLoadError && !coldLoadFetching && !paginating && !paginateError && replies.length === 0 && (
-          <div className={css.ThreadEmptyState}>
-            <Text size="T300" priority="400">
-              {t('Room.thread_no_replies')}
-            </Text>
-          </div>
-        )}
+        {thread &&
+          !coldLoadError &&
+          !coldLoadFetching &&
+          !paginating &&
+          !paginateError &&
+          replies.length === 0 && (
+            <div className={css.ThreadEmptyState}>
+              <Text size="T300" priority="400">
+                {t('Room.thread_no_replies')}
+              </Text>
+            </div>
+          )}
         {/* Top sentinel — IntersectionObserver triggers paginate when
             scrolled into view. Element-web onFillRequest pattern. The
             sentinel only renders while back-pagination is possible:
             once SDK reports no more events, we drop it so the observer
             disconnects on next mount. */}
-        {replies.length > 0 && (
-          <div ref={setTopSentinel} aria-hidden="true" />
-        )}
+        {replies.length > 0 && <div ref={setTopSentinel} aria-hidden="true" />}
         {paginating && replies.length > 0 && (
           <Box alignItems="Center" justifyContent="Center" style={{ padding: config.space.S200 }}>
             <Spinner size="200" />
@@ -1336,13 +1299,12 @@ export function ThreadDrawer({
   }
 
   return (
-    <div
-      ref={resizableRef}
-      className={css.ThreadDrawerResizable}
-      style={{ width: drawerWidth }}
-    >
+    <div ref={resizableRef} className={css.ThreadDrawerResizable} style={{ width: drawerWidth }}>
       {asideContent}
       {canResize && (
+        // Canonical WAI-ARIA window-splitter pattern (focusable separator
+        // with current/min/max). See Page.tsx for the same justification.
+        // eslint-disable-next-line jsx-a11y/no-noninteractive-element-interactions, jsx-a11y/role-supports-aria-props, jsx-a11y/no-noninteractive-tabindex
         <div
           ref={resizeHandleRef}
           role="separator"
@@ -1351,6 +1313,7 @@ export function ThreadDrawer({
           aria-valuemin={THREAD_DRAWER_WIDTH_MIN}
           aria-valuemax={drawerMaxW}
           aria-label="Resize thread drawer"
+          // eslint-disable-next-line jsx-a11y/no-noninteractive-tabindex
           tabIndex={0}
           className={css.ThreadDrawerResizeHandle}
           data-dragging={dragging || undefined}
diff --git a/src/app/features/room/message/CallMessage.tsx b/src/app/features/room/message/CallMessage.tsx
index e6eb1c33..7c5300fc 100644
--- a/src/app/features/room/message/CallMessage.tsx
+++ b/src/app/features/room/message/CallMessage.tsx
@@ -110,8 +110,7 @@ export function CallMessage({
   const senderId = aggregate.anchorSenderId;
   const isOwnMessage = !!mx.getUserId() && senderId === mx.getUserId();
   const peerBg = !isOwnMessage;
-  const senderName =
-    getMemberDisplayName(room, senderId) || getMxIdLocalPart(senderId) || senderId;
+  const senderName = getMemberDisplayName(room, senderId) || getMxIdLocalPart(senderId) || senderId;
 
   const tagColor = memberPowerTag?.color
     ? accessibleTagColors?.get(memberPowerTag.color)
@@ -148,11 +147,14 @@ export function CallMessage({
   })();
 
   const iconSrc = wasAnswered || ongoing ? Icons.Phone : Icons.PhoneDown;
-  const iconColor = ongoing
-    ? color.Success.Main
-    : wasAnswered
-      ? color.Surface.OnContainer
-      : color.Critical.Main;
+  let iconColor: string;
+  if (ongoing) {
+    iconColor = color.Success.Main;
+  } else if (wasAnswered) {
+    iconColor = color.Surface.OnContainer;
+  } else {
+    iconColor = color.Critical.Main;
+  }
 
   const bubbleBody = (
     <Box gap="300" alignItems="Center" style={{ minWidth: 0 }}>
@@ -194,11 +196,7 @@ export function CallMessage({
           isOwn={isOwnMessage}
           headerInBubble={channelHeaderInBubble}
           avatar={
-            <ChannelMessageAvatar
-              room={room}
-              senderId={senderId}
-              senderDisplayName={senderName}
-            />
+            <ChannelMessageAvatar room={room} senderId={senderId} senderDisplayName={senderName} />
           }
           header={
             <>
diff --git a/src/app/features/room/message/Message.tsx b/src/app/features/room/message/Message.tsx
index 14df89cb..c6fb00b3 100644
--- a/src/app/features/room/message/Message.tsx
+++ b/src/app/features/room/message/Message.tsx
@@ -34,6 +34,7 @@ import FocusTrap from 'focus-trap-react';
 import { useTranslation } from 'react-i18next';
 import { useHover, useFocusWithin } from 'react-aria';
 import { MatrixEvent, MsgType, Room } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { Relations } from 'matrix-js-sdk/lib/models/relations';
 import classNames from 'classnames';
 import { RoomPinnedEventsEventContent } from 'matrix-js-sdk/lib/types';
@@ -132,7 +133,7 @@ export const MessageAllReactionItem = as<
   return (
     <>
       <Overlay
-        onContextMenu={(evt: any) => {
+        onContextMenu={(evt: React.MouseEvent<HTMLDivElement>) => {
           evt.stopPropagation();
         }}
         open={open}
@@ -246,7 +247,8 @@ export const MessageSourceCodeItem = as<
       : evt.event;
 
   const getText = (): string => {
-    const evtId = mEvent.getId()!;
+    const evtId = mEvent.getId();
+    if (!evtId) return '';
     const evtTimeline = room.getTimelineForEvent(evtId);
     const edits =
       evtTimeline &&
@@ -364,7 +366,7 @@ export const MessagePinItem = as<
     if (!isPinned && eventId) {
       pinContent.pinned.push(eventId);
     }
-    mx.sendStateEvent(room.roomId, StateEvent.RoomPinnedEvents as any, pinContent);
+    mx.sendStateEvent(room.roomId, StateEvent.RoomPinnedEvents as keyof StateEvents, pinContent);
     onClose?.();
   };
 
@@ -845,7 +847,7 @@ export const Message = as<'div', MessageProps>(
 
     const handleContextMenu: MouseEventHandler<HTMLDivElement> = (evt) => {
       if (evt.altKey || !window.getSelection()?.isCollapsed || edit) return;
-      const tag = (evt.target as any).tagName;
+      const tag = (evt.target as Element).tagName;
       if (typeof tag === 'string' && tag.toLowerCase() === 'a') return;
       evt.preventDefault();
       setMenuAnchor({
@@ -918,11 +920,13 @@ export const Message = as<'div', MessageProps>(
                         returnFocusOnDeactivate={false}
                         allowTextCustomEmoji
                         onEmojiSelect={(key) => {
-                          onReactionToggle(mEvent.getId()!, key);
+                          const evtId = mEvent.getId();
+                          if (evtId) onReactionToggle(evtId, key);
                           setEmojiBoardAnchor(undefined);
                         }}
                         onCustomEmojiSelect={(mxc, shortcode) => {
-                          onReactionToggle(mEvent.getId()!, mxc, shortcode);
+                          const evtId = mEvent.getId();
+                          if (evtId) onReactionToggle(evtId, mxc, shortcode);
                           setEmojiBoardAnchor(undefined);
                         }}
                         requestClose={() => {
@@ -994,7 +998,8 @@ export const Message = as<'div', MessageProps>(
                         {canSendReaction && (
                           <MessageQuickReactions
                             onReaction={(key, shortcode) => {
-                              onReactionToggle(mEvent.getId()!, key, shortcode);
+                              const evtId = mEvent.getId();
+                              if (evtId) onReactionToggle(evtId, key, shortcode);
                               closeMenu();
                             }}
                           />
@@ -1030,7 +1035,7 @@ export const Message = as<'div', MessageProps>(
                               after={<Icon size="100" src={Icons.ReplyArrow} />}
                               radii="300"
                               data-event-id={mEvent.getId()}
-                              onClick={(evt: any) => {
+                              onClick={(evt: Parameters<typeof onReplyClick>[0]) => {
                                 onReplyClick(evt);
                                 closeMenu();
                               }}
@@ -1051,7 +1056,7 @@ export const Message = as<'div', MessageProps>(
                               after={<Icon src={Icons.ThreadPlus} size="100" />}
                               radii="300"
                               data-event-id={mEvent.getId()}
-                              onClick={(evt: any) => {
+                              onClick={(evt: Parameters<typeof onReplyClick>[0]) => {
                                 onReplyClick(evt, true);
                                 closeMenu();
                               }}
@@ -1173,11 +1178,7 @@ export const Message = as<'div', MessageProps>(
                         so the bubble header matches the DM-chat rhythm.
                         Channels main timeline keeps T400 for the prominent
                         avatar-and-name row above an unbordered body. */}
-                    <Text
-                      as="span"
-                      size={channelHeaderInBubble ? 'T200' : 'T400'}
-                      truncate
-                    >
+                    <Text as="span" size={channelHeaderInBubble ? 'T200' : 'T400'} truncate>
                       <UsernameBold>
                         {isOwnMessage ? t('Direct.message_me_label') : senderDisplayName}
                       </UsernameBold>
@@ -1269,7 +1270,7 @@ export const Event = as<'div', EventProps>(
 
     const handleContextMenu: MouseEventHandler<HTMLDivElement> = (evt) => {
       if (evt.altKey || !window.getSelection()?.isCollapsed) return;
-      const tag = (evt.target as any).tagName;
+      const tag = (evt.target as Element).tagName;
       if (typeof tag === 'string' && tag.toLowerCase() === 'a') return;
       evt.preventDefault();
       setMenuAnchor({
diff --git a/src/app/features/room/message/MessageEditor.tsx b/src/app/features/room/message/MessageEditor.tsx
index 8ab6afb0..7642191a 100644
--- a/src/app/features/room/message/MessageEditor.tsx
+++ b/src/app/features/room/message/MessageEditor.tsx
@@ -22,6 +22,7 @@ import {
 import { Editor, Transforms } from 'slate';
 import { ReactEditor } from 'slate-react';
 import { IContent, IMentions, MatrixEvent, RelationType, Room } from 'matrix-js-sdk';
+import type { RoomMessageEventContent } from 'matrix-js-sdk/lib/types';
 import { isKeyHotkey } from 'is-hotkey';
 import {
   AUTOCOMPLETE_PREFIXES,
@@ -80,7 +81,8 @@ export const MessageEditor = as<'div', MessageEditorProps>(
       string | undefined,
       IMentions | undefined
     ] => {
-      const evtId = mEvent.getId()!;
+      const evtId = mEvent.getId();
+      if (!evtId) return [undefined, undefined, undefined];
       const evtTimeline = room.getTimelineForEvent(evtId);
       const editedEvent =
         evtTimeline && getEditedEvent(evtId, mEvent, evtTimeline.getTimelineSet());
@@ -170,7 +172,11 @@ export const MessageEditor = as<'div', MessageEditorProps>(
         // /sync round-trip — same lag as M4 receipts. Optimistic
         // local-replace via `mEvent.makeReplaced(localEvent)` is
         // tracked for follow-up.
-        return mx.sendMessage(roomId, mEvent.threadRootId ?? null, content as any);
+        return mx.sendMessage(
+          roomId,
+          mEvent.threadRootId ?? null,
+          content as RoomMessageEventContent
+        );
       }, [mx, editor, roomId, mEvent, isMarkdown, getPrevBodyAndFormattedBody])
     );
 
diff --git a/src/app/features/room/message/Reactions.tsx b/src/app/features/room/message/Reactions.tsx
index f0f308bb..0bd8d929 100644
--- a/src/app/features/room/message/Reactions.tsx
+++ b/src/app/features/room/message/Reactions.tsx
@@ -96,7 +96,7 @@ export const Reactions = as<'div', ReactionsProps>(
         })}
         {reactions.length > 0 && (
           <Overlay
-            onContextMenu={(evt: any) => {
+            onContextMenu={(evt: React.MouseEvent<HTMLDivElement>) => {
               evt.stopPropagation();
             }}
             open={!!viewer}
diff --git a/src/app/features/room/message/useMessageInteractionHandlers.ts b/src/app/features/room/message/useMessageInteractionHandlers.ts
index 977ee443..b96d4e76 100644
--- a/src/app/features/room/message/useMessageInteractionHandlers.ts
+++ b/src/app/features/room/message/useMessageInteractionHandlers.ts
@@ -2,7 +2,8 @@ import { MouseEvent, MouseEventHandler, useCallback, useState } from 'react';
 import { useNavigate } from 'react-router-dom';
 import { Editor } from 'slate';
 import { ReactEditor } from 'slate-react';
-import { IContent, Room } from 'matrix-js-sdk';
+import { EventType, IContent, Room } from 'matrix-js-sdk';
+import type { ReactionEventContent } from 'matrix-js-sdk/lib/types';
 
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
 import { useOpenUserRoomProfile } from '../../../state/hooks/userRoomProfile';
@@ -14,13 +15,8 @@ import {
   getMemberDisplayName,
   getReactionContent,
 } from '../../../utils/room';
-import {
-  eventWithShortcode,
-  factoryEventSentBy,
-  getMxIdLocalPart,
-} from '../../../utils/matrix';
+import { eventWithShortcode, factoryEventSentBy, getMxIdLocalPart } from '../../../utils/matrix';
 import { IReplyDraft } from '../../../state/room/roomInputDrafts';
-import { MessageEvent } from '../../../../types/matrix/room';
 import { getChannelsThreadPath } from '../../../pages/pathUtils';
 
 export type UseMessageInteractionHandlersOptions = {
@@ -60,15 +56,8 @@ export type MessageInteractionHandlers = {
   handleOpenReply: MouseEventHandler;
   handleUserClick: MouseEventHandler<HTMLButtonElement>;
   handleUsernameClick: MouseEventHandler<HTMLButtonElement>;
-  handleReplyClick: (
-    ev: MouseEvent<HTMLButtonElement>,
-    startThread?: boolean
-  ) => void;
-  handleReactionToggle: (
-    targetEventId: string,
-    key: string,
-    shortcode?: string
-  ) => void;
+  handleReplyClick: (ev: MouseEvent<HTMLButtonElement>, startThread?: boolean) => void;
+  handleReactionToggle: (targetEventId: string, key: string, shortcode?: string) => void;
 };
 
 // Wiring layer for `<Message>` event-handler props, shared between
@@ -166,13 +155,7 @@ export function useMessageInteractionHandlers({
       // draft. Bridged rooms (Telegram puppets etc.) have no thread
       // semantic on the bridge side — fall back to the legacy
       // m.in_reply_to draft path so messages still go through.
-      if (
-        startThread &&
-        channelsMode &&
-        !isBridged &&
-        spaceIdOrAlias &&
-        roomIdOrAlias
-      ) {
+      if (startThread && channelsMode && !isBridged && spaceIdOrAlias && roomIdOrAlias) {
         // useParams returns the encoded URL value; getChannelsThreadPath
         // re-encodes via generatePath so we decode once first to avoid
         // double-encoding (matches `routeParent.ts` decode pattern).
@@ -206,16 +189,7 @@ export function useMessageInteractionHandlers({
         setTimeout(() => ReactEditor.focus(editor), 100);
       }
     },
-    [
-      room,
-      setReplyDraft,
-      editor,
-      channelsMode,
-      isBridged,
-      navigate,
-      spaceIdOrAlias,
-      roomIdOrAlias,
-    ]
+    [room, setReplyDraft, editor, channelsMode, isBridged, navigate, spaceIdOrAlias, roomIdOrAlias]
   );
 
   const handleReactionToggle = useCallback(
@@ -224,10 +198,12 @@ export function useMessageInteractionHandlers({
       const allReactions = relations?.getSortedAnnotationsByKey() ?? [];
       const [, reactionsSet] = allReactions.find(([k]) => k === key) ?? [];
       const reactions = reactionsSet ? Array.from(reactionsSet) : [];
-      const myReaction = reactions.find(factoryEventSentBy(mx.getUserId()!));
+      const myUserId = mx.getUserId();
+      const myReaction = myUserId ? reactions.find(factoryEventSentBy(myUserId)) : undefined;
 
       if (myReaction && !!myReaction?.isRelation()) {
-        mx.redactEvent(room.roomId, myReaction.getId()!);
+        const reactionId = myReaction.getId();
+        if (reactionId) mx.redactEvent(room.roomId, reactionId);
         return;
       }
       const rShortcode =
@@ -235,8 +211,8 @@ export function useMessageInteractionHandlers({
         (reactions.find(eventWithShortcode)?.getContent().shortcode as string | undefined);
       mx.sendEvent(
         room.roomId,
-        MessageEvent.Reaction as any,
-        getReactionContent(targetEventId, key, rShortcode)
+        EventType.Reaction,
+        getReactionContent(targetEventId, key, rShortcode) as ReactionEventContent
       );
     },
     [mx, room]
diff --git a/src/app/features/room/msgContent.ts b/src/app/features/room/msgContent.ts
index 5b7cd145..1089af62 100644
--- a/src/app/features/room/msgContent.ts
+++ b/src/app/features/room/msgContent.ts
@@ -50,6 +50,10 @@ export const getImageMsgContent = async (
 ): Promise<IContent> => {
   const { file, originalFile, encInfo, metadata } = item;
   const [imgError, imgEl] = await to(loadImageElement(getImageFileUrl(originalFile)));
+  // Non-fatal: upload continues without dimensions/blurhash when the
+  // browser can't decode the image. Surfacing in the dev console helps
+  // diagnose broken codecs without blocking the user's send.
+  // eslint-disable-next-line no-console
   if (imgError) console.warn(imgError);
 
   const content: IContent = {
@@ -85,6 +89,8 @@ export const getVideoMsgContent = async (
   const { file, originalFile, encInfo, metadata } = item;
 
   const [videoError, videoEl] = await to(loadVideoElement(getVideoFileUrl(originalFile)));
+  // Same justification as image branch above.
+  // eslint-disable-next-line no-console
   if (videoError) console.warn(videoError);
 
   const content: IContent = {
@@ -109,6 +115,7 @@ export const getVideoMsgContent = async (
         scaleYDimension(videoEl.videoWidth, 512, videoEl.videoHeight)
       );
     }
+    // eslint-disable-next-line no-console
     if (thumbError) console.warn(thumbError);
     content.info = {
       ...getVideoInfo(videoEl, file),
diff --git a/src/app/features/room/reaction-viewer/ReactionViewer.tsx b/src/app/features/room/reaction-viewer/ReactionViewer.tsx
index 6c686bc5..16f0a185 100644
--- a/src/app/features/room/reaction-viewer/ReactionViewer.tsx
+++ b/src/app/features/room/reaction-viewer/ReactionViewer.tsx
@@ -132,7 +132,7 @@ export const ReactionViewer = as<'div', ReactionViewerProps>(
                       key={senderId}
                       style={{ padding: `0 ${config.space.S200}` }}
                       radii="400"
-                      onClick={(event) => {
+                      onClick={(event: React.MouseEvent<HTMLButtonElement>) => {
                         openProfile(
                           room.roomId,
                           space?.roomId,
diff --git a/src/app/features/room/room-pin-menu/RoomPinMenu.tsx b/src/app/features/room/room-pin-menu/RoomPinMenu.tsx
index 5be18fe7..141afd2d 100644
--- a/src/app/features/room/room-pin-menu/RoomPinMenu.tsx
+++ b/src/app/features/room/room-pin-menu/RoomPinMenu.tsx
@@ -1,6 +1,7 @@
 /* eslint-disable react/destructuring-assignment */
 import React, { forwardRef, MouseEventHandler, useCallback, useMemo, useRef } from 'react';
 import { MatrixEvent, Room } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { RoomPinnedEventsEventContent } from 'matrix-js-sdk/lib/types';
 import { useTranslation } from 'react-i18next';
 import {
@@ -121,7 +122,11 @@ function PinnedMessage({
         pinned: content.pinned.filter((id) => id !== eventId),
       };
 
-      return mx.sendStateEvent(room.roomId, StateEvent.RoomPinnedEvents as any, newContent);
+      return mx.sendStateEvent(
+        room.roomId,
+        StateEvent.RoomPinnedEvents as keyof StateEvents,
+        newContent
+      );
     }, [room, eventId, mx])
   );
 
@@ -172,7 +177,7 @@ function PinnedMessage({
       </Box>
     );
 
-  const sender = pinnedEvent.getSender()!;
+  const sender = pinnedEvent.getSender() ?? '';
   const displayName = getMemberDisplayName(room, sender) ?? getMxIdLocalPart(sender) ?? sender;
   const senderAvatarMxc = getMemberAvatarMxc(room, sender);
   const getContent = (() => pinnedEvent.getContent()) as GetContentCallback;
@@ -245,7 +250,7 @@ export const RoomPinMenu = forwardRef<HTMLDivElement, RoomPinMenuProps>(
   ({ room, requestClose }, ref) => {
     const { t } = useTranslation();
     const mx = useMatrixClient();
-    const userId = mx.getUserId()!;
+    const userId = mx.getSafeUserId();
     const powerLevels = usePowerLevelsContext();
     const creators = useRoomCreators(room);
 
@@ -329,12 +334,12 @@ export const RoomPinMenu = forwardRef<HTMLDivElement, RoomPinMenuProps>(
           );
         },
         [MessageEvent.RoomMessageEncrypted]: (event, displayName) => {
-          const eventId = event.getId()!;
-          const evtTimeline = room.getTimelineForEvent(eventId);
+          const eventId = event.getId();
+          const evtTimeline = eventId ? room.getTimelineForEvent(eventId) : undefined;
 
           const mEvent = evtTimeline?.getEvents().find((e) => e.getId() === eventId);
 
-          if (!mEvent || !evtTimeline) {
+          if (!mEvent || !evtTimeline || !eventId) {
             return (
               <Box grow="Yes" direction="Column">
                 <Text size="T400" priority="300">
diff --git a/src/app/features/settings/account/MatrixId.tsx b/src/app/features/settings/account/MatrixId.tsx
index 6911cedb..4e283313 100644
--- a/src/app/features/settings/account/MatrixId.tsx
+++ b/src/app/features/settings/account/MatrixId.tsx
@@ -1,7 +1,7 @@
 import React from 'react';
 import { Box, Text, Chip } from 'folds';
 import { useTranslation } from 'react-i18next';
-import { useMatrixClient } from '../../../hooks/useMatrixClient';
+import { useAuthedUserId } from '../../../hooks/useAuthedUserId';
 import { SequenceCard } from '../../../components/sequence-card';
 import { SequenceCardStyle } from '../styles.css';
 import { SettingTile } from '../../../components/setting-tile';
@@ -9,18 +9,12 @@ import { copyToClipboard } from '../../../utils/dom';
 
 export function MatrixId() {
   const { t } = useTranslation();
-  const mx = useMatrixClient();
-  const userId = mx.getUserId()!;
+  const userId = useAuthedUserId();
 
   return (
     <Box direction="Column" gap="100">
       <Text size="L400">{t('Settings.matrix_id')}</Text>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <SettingTile
           title={userId}
           after={
diff --git a/src/app/features/settings/account/Profile.tsx b/src/app/features/settings/account/Profile.tsx
index 3b201849..398b0877 100644
--- a/src/app/features/settings/account/Profile.tsx
+++ b/src/app/features/settings/account/Profile.tsx
@@ -30,6 +30,7 @@ import { SequenceCard } from '../../../components/sequence-card';
 import { SequenceCardStyle } from '../styles.css';
 import { SettingTile } from '../../../components/setting-tile';
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
+import { useAuthedUserId } from '../../../hooks/useAuthedUserId';
 import { UserProfile, useUserProfile } from '../../../hooks/useUserProfile';
 import { getMxIdLocalPart, mxcUrlToHttp } from '../../../utils/matrix';
 import { UserAvatar } from '../../../components/user-avatar';
@@ -308,19 +309,13 @@ function ProfileDisplayName({ profile, userId }: ProfileProps) {
 
 export function Profile() {
   const { t } = useTranslation();
-  const mx = useMatrixClient();
-  const userId = mx.getUserId()!;
+  const userId = useAuthedUserId();
   const profile = useUserProfile(userId);
 
   return (
     <Box direction="Column" gap="100">
       <Text size="L400">{t('Settings.profile')}</Text>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <ProfileAvatar userId={userId} profile={profile} />
         <ProfileDisplayName userId={userId} profile={profile} />
       </SequenceCard>
diff --git a/src/app/features/settings/developer-tools/DevelopTools.tsx b/src/app/features/settings/developer-tools/DevelopTools.tsx
index 19c53d25..cba7b666 100644
--- a/src/app/features/settings/developer-tools/DevelopTools.tsx
+++ b/src/app/features/settings/developer-tools/DevelopTools.tsx
@@ -1,4 +1,5 @@
 import React, { useCallback, useState } from 'react';
+import type { AccountDataEvents } from 'matrix-js-sdk';
 import { useTranslation } from 'react-i18next';
 import { Box, Text, IconButton, Icon, Icons, Scroll, Switch, Button } from 'folds';
 import { Page, PageContent, PageHeader } from '../../../components/page';
@@ -27,7 +28,8 @@ export function DeveloperTools({ requestClose }: DeveloperToolsProps) {
 
   const submitAccountData: AccountDataSubmitCallback = useCallback(
     async (type, content) => {
-      await mx.setAccountData(type, content);
+      // Dev tool accepts arbitrary keys; SDK signature wants `keyof AccountDataEvents`.
+      await mx.setAccountData(type as keyof AccountDataEvents, content);
     },
     [mx]
   );
@@ -36,7 +38,11 @@ export function DeveloperTools({ requestClose }: DeveloperToolsProps) {
     return (
       <AccountDataEditor
         type={accountDataType ?? undefined}
-        content={accountDataType ? mx.getAccountData(accountDataType)?.getContent() : undefined}
+        content={
+          accountDataType
+            ? mx.getAccountData(accountDataType as keyof AccountDataEvents)?.getContent()
+            : undefined
+        }
         submitChange={submitAccountData}
         requestClose={() => setAccountDataType(undefined)}
       />
@@ -53,7 +59,11 @@ export function DeveloperTools({ requestClose }: DeveloperToolsProps) {
             </Text>
           </Box>
           <Box shrink="No">
-            <IconButton onClick={requestClose} variant="SurfaceVariant" aria-label={t('Settings.close')}>
+            <IconButton
+              onClick={requestClose}
+              variant="SurfaceVariant"
+              aria-label={t('Settings.close')}
+            >
               <Icon src={Icons.Cross} />
             </IconButton>
           </Box>
diff --git a/src/app/features/settings/emojis-stickers/GlobalPacks.tsx b/src/app/features/settings/emojis-stickers/GlobalPacks.tsx
index 0d12d59e..44c5c686 100644
--- a/src/app/features/settings/emojis-stickers/GlobalPacks.tsx
+++ b/src/app/features/settings/emojis-stickers/GlobalPacks.tsx
@@ -141,7 +141,7 @@ function GlobalPackSelector({
               if (!room) return null;
               const roomPackAddresses = roomPacks
                 .map((pack) => pack.address)
-                .filter((addr) => addr !== undefined);
+                .filter((addr): addr is PackAddress => addr !== undefined);
               const allSelected = roomPackAddresses.every((addr) =>
                 selected.find((address) => packAddressEqual(addr, address))
               );
diff --git a/src/app/features/settings/emojis-stickers/UserPack.tsx b/src/app/features/settings/emojis-stickers/UserPack.tsx
index fa4687a6..f86050b7 100644
--- a/src/app/features/settings/emojis-stickers/UserPack.tsx
+++ b/src/app/features/settings/emojis-stickers/UserPack.tsx
@@ -26,7 +26,7 @@ export function UserPack({ onViewPack }: UserPackProps) {
     if (userPack) {
       onViewPack(userPack);
     } else {
-      const defaultPack = new ImagePack(mx.getUserId() ?? '', {}, undefined);
+      const defaultPack = new ImagePack(mx.getSafeUserId(), {}, undefined);
       onViewPack(defaultPack);
     }
   };
@@ -34,12 +34,7 @@ export function UserPack({ onViewPack }: UserPackProps) {
   return (
     <Box direction="Column" gap="100">
       <Text size="L400">{t('Settings.default_pack')}</Text>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <SettingTile
           title={userPack?.meta.name ?? t('Settings.unknown')}
           description={userPack?.meta.attribution}
diff --git a/src/app/features/settings/notifications/SpecialMessages.tsx b/src/app/features/settings/notifications/SpecialMessages.tsx
index 3609bdc6..e2b3d828 100644
--- a/src/app/features/settings/notifications/SpecialMessages.tsx
+++ b/src/app/features/settings/notifications/SpecialMessages.tsx
@@ -8,6 +8,7 @@ import { SequenceCard } from '../../../components/sequence-card';
 import { SequenceCardStyle } from '../styles.css';
 import { SettingTile } from '../../../components/setting-tile';
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
+import { useAuthedUserId } from '../../../hooks/useAuthedUserId';
 import { useUserProfile } from '../../../hooks/useUserProfile';
 import { getMxIdLocalPart } from '../../../utils/matrix';
 import { makePushRuleData, PushRuleData, usePushRule } from '../../../hooks/usePushRule';
@@ -114,8 +115,7 @@ function MentionModeSwitcher({ ruleId, pushRules, defaultPushRuleData }: PushRul
 
 export function SpecialMessagesNotifications() {
   const { t } = useTranslation();
-  const mx = useMatrixClient();
-  const userId = mx.getUserId()!;
+  const userId = useAuthedUserId();
   const { displayName } = useUserProfile(userId);
   const pushRulesEvt = useAccountData(AccountDataEvent.PushRules);
   const pushRules = useMemo(
@@ -134,12 +134,7 @@ export function SpecialMessagesNotifications() {
           </Badge>
         </Box>
       </Box>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <SettingTile
           title={t('Settings.mention_user_id', { userId })}
           after={
@@ -151,12 +146,7 @@ export function SpecialMessagesNotifications() {
           }
         />
       </SequenceCard>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <SettingTile
           title={
             displayName
@@ -172,12 +162,7 @@ export function SpecialMessagesNotifications() {
           }
         />
       </SequenceCard>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <SettingTile
           title={t('Settings.contains_username', { username: getMxIdLocalPart(userId) })}
           after={
@@ -189,12 +174,7 @@ export function SpecialMessagesNotifications() {
           }
         />
       </SequenceCard>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <SettingTile
           title={t('Settings.mention_room')}
           after={
@@ -206,12 +186,7 @@ export function SpecialMessagesNotifications() {
           }
         />
       </SequenceCard>
-      <SequenceCard
-        className={SequenceCardStyle}
-        variant="Background"
-        direction="Column"
-        gap="400"
-      >
+      <SequenceCard className={SequenceCardStyle} variant="Background" direction="Column" gap="400">
         <SettingTile
           title={t('Settings.contains_room')}
           after={
diff --git a/src/app/hooks/useAccountData.ts b/src/app/hooks/useAccountData.ts
index 30e47b47..a540f5cd 100644
--- a/src/app/hooks/useAccountData.ts
+++ b/src/app/hooks/useAccountData.ts
@@ -1,10 +1,14 @@
 import { useState, useCallback } from 'react';
+import type { AccountDataEvents } from 'matrix-js-sdk';
 import { useMatrixClient } from './useMatrixClient';
 import { useAccountDataCallback } from './useAccountDataCallback';
 
 export function useAccountData(eventType: string) {
   const mx = useMatrixClient();
-  const [event, setEvent] = useState(() => mx.getAccountData(eventType));
+  // Generic hook accepts arbitrary string keys (incl. custom Vojo / Ponies
+  // event-types augmented in sdkAugmentation.d.ts and one-off dev-tool keys).
+  // Cast through `keyof AccountDataEvents` to satisfy the SDK literal-union.
+  const [event, setEvent] = useState(() => mx.getAccountData(eventType as keyof AccountDataEvents));
 
   useAccountDataCallback(
     mx,
diff --git a/src/app/hooks/useAuthedUserId.ts b/src/app/hooks/useAuthedUserId.ts
new file mode 100644
index 00000000..cc75a418
--- /dev/null
+++ b/src/app/hooks/useAuthedUserId.ts
@@ -0,0 +1,16 @@
+import { useMatrixClient } from './useMatrixClient';
+
+// Returns the current user's MXID in any subtree that mounts only after
+// authentication has resolved (`<ClientLayout>` and everything inside it).
+// Throws if the SDK has no user ID — that's an invariant violation, not a
+// soft-failure path: by the time post-login components render, the SDK
+// already has a session. Prefer this over `mx.getUserId() ?? ''` so a
+// broken invariant surfaces loudly instead of silently defaulting to '' and
+// writing empty-string user IDs into account-data / storage keys.
+//
+// For utility functions that aren't React hooks, call `mx.getSafeUserId()`
+// directly — it's the same contract.
+export function useAuthedUserId(): string {
+  const mx = useMatrixClient();
+  return mx.getSafeUserId();
+}
diff --git a/src/app/hooks/useCommands.ts b/src/app/hooks/useCommands.ts
index c02b0e94..61a88988 100644
--- a/src/app/hooks/useCommands.ts
+++ b/src/app/hooks/useCommands.ts
@@ -9,6 +9,7 @@ import {
   RoomMember,
   Visibility,
 } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { RoomServerAclEventContent } from 'matrix-js-sdk/lib/types';
 import { useMemo } from 'react';
 import {
@@ -366,7 +367,7 @@ export const useCommands = (mx: MatrixClient, room: Room): CommandRecord => {
           if (!content) return;
           await mx.sendStateEvent(
             room.roomId,
-            StateEvent.RoomMember as any,
+            StateEvent.RoomMember as keyof StateEvents,
             {
               ...content,
               displayname: nick,
@@ -388,7 +389,7 @@ export const useCommands = (mx: MatrixClient, room: Room): CommandRecord => {
             if (!content) return;
             await mx.sendStateEvent(
               room.roomId,
-              StateEvent.RoomMember as any,
+              StateEvent.RoomMember as keyof StateEvents,
               {
                 ...content,
                 avatar_url: payload,
@@ -528,7 +529,11 @@ export const useCommands = (mx: MatrixClient, room: Room): CommandRecord => {
           aclContent.allow?.sort();
           aclContent.deny?.sort();
 
-          await mx.sendStateEvent(room.roomId, StateEvent.RoomServerAcl as any, aclContent);
+          await mx.sendStateEvent(
+            room.roomId,
+            StateEvent.RoomServerAcl as keyof StateEvents,
+            aclContent
+          );
         },
       },
     }),
diff --git a/src/app/hooks/useDotColor.ts b/src/app/hooks/useDotColor.ts
index 6dbf8334..a71c0aa8 100644
--- a/src/app/hooks/useDotColor.ts
+++ b/src/app/hooks/useDotColor.ts
@@ -37,20 +37,20 @@ export function useDotColor(
   hideReadReceipts = false
 ): DotColor {
   const mx = useMatrixClient();
-  const myUserId = mx.getUserId() ?? '';
+  const myUserId = mx.getSafeUserId();
   const senderId = mEvent.getSender() ?? '';
-  const isOwn = !!myUserId && senderId === myUserId;
+  const isOwn = senderId === myUserId;
   const eventId = mEvent.getId();
 
   const status = useMessageStatus(room, mEvent);
 
   const [haveSeen, setHaveSeen] = useState<boolean>(() =>
-    enabled && !isOwn && !!eventId && !!myUserId ? room.hasUserReadEvent(myUserId, eventId) : false
+    enabled && !isOwn && !!eventId ? room.hasUserReadEvent(myUserId, eventId) : false
   );
 
   useEffect(() => {
     if (!enabled) return undefined;
-    if (isOwn || !eventId || !myUserId) return undefined;
+    if (isOwn || !eventId) return undefined;
     setHaveSeen(room.hasUserReadEvent(myUserId, eventId));
     const handler: RoomEventHandlerMap[RoomEvent.Receipt] = (_event, r) => {
       if (r.roomId !== room.roomId) return;
diff --git a/src/app/hooks/useMessageStatus.ts b/src/app/hooks/useMessageStatus.ts
index 41001773..040972b8 100644
--- a/src/app/hooks/useMessageStatus.ts
+++ b/src/app/hooks/useMessageStatus.ts
@@ -40,7 +40,7 @@ function getDeliveryStatus(
 
 export function useMessageStatus(room: Room, mEvent: MatrixEvent): MessageDeliveryStatus | null {
   const mx = useMatrixClient();
-  const myUserId = mx.getUserId() ?? '';
+  const myUserId = mx.getSafeUserId();
   const isOwnMessage = mEvent.getSender() === myUserId;
 
   const [status, setStatus] = useState<MessageDeliveryStatus | null>(() =>
diff --git a/src/app/hooks/usePowerLevelTags.ts b/src/app/hooks/usePowerLevelTags.ts
index ffad45c9..a41fc1d4 100644
--- a/src/app/hooks/usePowerLevelTags.ts
+++ b/src/app/hooks/usePowerLevelTags.ts
@@ -12,14 +12,8 @@ const sortPowers = (powers: number[]): number[] => powers.sort(powerSortFn);
 
 export const getPowers = (tags: PowerLevelTags): number[] => {
   const powers: number[] = Object.keys(tags)
-    .map((p) => {
-      const power = parseInt(p, 10);
-      if (Number.isNaN(power)) {
-        return undefined;
-      }
-      return power;
-    })
-    .filter((power) => typeof power === 'number');
+    .map((p) => parseInt(p, 10))
+    .filter((power): power is number => !Number.isNaN(power));
 
   return sortPowers(powers);
 };
diff --git a/src/app/hooks/usePowerLevels.ts b/src/app/hooks/usePowerLevels.ts
index 0281b23c..a39ccb19 100644
--- a/src/app/hooks/usePowerLevels.ts
+++ b/src/app/hooks/usePowerLevels.ts
@@ -46,7 +46,8 @@ const fillMissingPowers = (powerLevels: IPowerLevels): IPowerLevels =>
     const keys = Object.keys(DEFAULT_POWER_LEVELS) as unknown as (keyof IPowerLevels)[];
     keys.forEach((key) => {
       if (draftPl[key] === undefined) {
-        // eslint-disable-next-line no-param-reassign
+        // Distributive union over IPowerLevels keys breaks TS narrowing across the indexed write.
+        // eslint-disable-next-line no-param-reassign, @typescript-eslint/no-explicit-any
         draftPl[key] = DEFAULT_POWER_LEVELS[key] as any;
       }
     });
diff --git a/src/app/hooks/useRoomAliases.ts b/src/app/hooks/useRoomAliases.ts
index 005ff0b6..e1684fcc 100644
--- a/src/app/hooks/useRoomAliases.ts
+++ b/src/app/hooks/useRoomAliases.ts
@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useMemo } from 'react';
 import { MatrixError, Room } from 'matrix-js-sdk';
+import type { StateEvents } from 'matrix-js-sdk';
 import { RoomCanonicalAliasEventContent } from 'matrix-js-sdk/lib/types';
 import { AsyncState, useAsyncCallback } from './useAsyncCallback';
 import { useMatrixClient } from './useMatrixClient';
@@ -56,7 +57,11 @@ export const useSetMainAlias = (room: Room): ((alias: string | undefined) => Pro
         alt_aliases: altAliases,
       };
 
-      await mx.sendStateEvent(room.roomId, StateEvent.RoomCanonicalAlias as any, newContent);
+      await mx.sendStateEvent(
+        room.roomId,
+        StateEvent.RoomCanonicalAlias as keyof StateEvents,
+        newContent
+      );
     },
     [mx, room]
   );
@@ -90,7 +95,11 @@ export const usePublishUnpublishAliases = (
         alt_aliases: altAliases,
       };
 
-      await mx.sendStateEvent(room.roomId, StateEvent.RoomCanonicalAlias as any, newContent);
+      await mx.sendStateEvent(
+        room.roomId,
+        StateEvent.RoomCanonicalAlias as keyof StateEvents,
+        newContent
+      );
     },
     [mx, room]
   );
@@ -114,7 +123,11 @@ export const usePublishUnpublishAliases = (
         alt_aliases: altAliases,
       };
 
-      await mx.sendStateEvent(room.roomId, StateEvent.RoomCanonicalAlias as any, newContent);
+      await mx.sendStateEvent(
+        room.roomId,
+        StateEvent.RoomCanonicalAlias as keyof StateEvents,
+        newContent
+      );
     },
     [mx, room]
   );
diff --git a/src/app/hooks/useRoomMeta.ts b/src/app/hooks/useRoomMeta.ts
index d9920557..cb5c7fdd 100644
--- a/src/app/hooks/useRoomMeta.ts
+++ b/src/app/hooks/useRoomMeta.ts
@@ -1,11 +1,6 @@
 import { useEffect, useState } from 'react';
 import { RoomJoinRulesEventContent } from 'matrix-js-sdk/lib/types';
-import {
-  Room,
-  RoomEvent,
-  RoomEventHandlerMap,
-  RoomStateEvent,
-} from 'matrix-js-sdk';
+import { Room, RoomEvent, RoomStateEvent } from 'matrix-js-sdk';
 import { StateEvent } from '../../types/matrix/room';
 import { useStateEvent } from './useStateEvent';
 
@@ -39,9 +34,7 @@ const resolveRoomName = (room: Room): string => {
       if (peer.rawDisplayName && peer.rawDisplayName.trim()) {
         return peer.rawDisplayName.trim();
       }
-      const local = peer.userId.startsWith('@')
-        ? peer.userId.slice(1).split(':')[0]
-        : peer.userId;
+      const local = peer.userId.startsWith('@') ? peer.userId.slice(1).split(':')[0] : peer.userId;
       return local || peer.userId;
     }
   }
@@ -67,7 +60,10 @@ export const useRoomName = (room: Room): string => {
   useEffect(() => {
     setName(resolveRoomName(room));
 
-    const recompute: RoomEventHandlerMap[RoomEvent.Name] = () => {
+    // No-arg form keeps the same callback assignable to both RoomEvent.Name
+    // (event handler is `(room: Room) => void`) and RoomStateEvent.Members
+    // (`(event, state, member) => void`); we ignore the args either way.
+    const recompute = () => {
       setName(resolveRoomName(room));
     };
     // RoomEvent.Name fires when m.room.name changes;
diff --git a/src/app/pages/auth/AuthMascot.tsx b/src/app/pages/auth/AuthMascot.tsx
index a51abf99..c36f5070 100644
--- a/src/app/pages/auth/AuthMascot.tsx
+++ b/src/app/pages/auth/AuthMascot.tsx
@@ -1,11 +1,7 @@
 import React, { Ref, useCallback, useEffect, useLayoutEffect, useRef } from 'react';
 
 import { launchSplash } from '../../plugins/launchSplash';
-import {
-  attachMascotVideo,
-  detachMascotVideo,
-  mascotVideoReady,
-} from './mascotSingleton';
+import { attachMascotVideo, detachMascotVideo, mascotVideoReady } from './mascotSingleton';
 import * as css from './styles.css';
 
 type AuthMascotProps = {
@@ -64,8 +60,13 @@ export function AuthMascot({ mascotRef, centered }: AuthMascotProps) {
   const setRefs = useCallback(
     (node: HTMLDivElement | null) => {
       containerRef.current = node;
-      if (typeof mascotRef === 'function') mascotRef(node);
-      else if (mascotRef && typeof mascotRef === 'object') {
+      if (typeof mascotRef === 'function') {
+        mascotRef(node);
+      } else if (mascotRef && typeof mascotRef === 'object') {
+        // Forward-ref mutation is the canonical React pattern for combining
+        // refs; the eslint rule fires on any param mutation, but a MutableRefObject
+        // is specifically designed for this.
+        // eslint-disable-next-line no-param-reassign
         (mascotRef as React.MutableRefObject<HTMLDivElement | null>).current = node;
       }
     },
diff --git a/src/app/pages/client/ClientInitStorageAtom.tsx b/src/app/pages/client/ClientInitStorageAtom.tsx
index 5793bb6b..c57ca95d 100644
--- a/src/app/pages/client/ClientInitStorageAtom.tsx
+++ b/src/app/pages/client/ClientInitStorageAtom.tsx
@@ -1,5 +1,5 @@
 import React, { ReactNode, useMemo } from 'react';
-import { useMatrixClient } from '../../hooks/useMatrixClient';
+import { useAuthedUserId } from '../../hooks/useAuthedUserId';
 import { makeClosedNavCategoriesAtom } from '../../state/closedNavCategories';
 import { ClosedNavCategoriesProvider } from '../../state/hooks/closedNavCategories';
 import { makeClosedLobbyCategoriesAtom } from '../../state/closedLobbyCategories';
@@ -15,8 +15,7 @@ type ClientInitStorageAtomProps = {
   children: ReactNode;
 };
 export function ClientInitStorageAtom({ children }: ClientInitStorageAtomProps) {
-  const mx = useMatrixClient();
-  const userId = mx.getUserId()!;
+  const userId = useAuthedUserId();
 
   const closedNavCategoriesAtom = useMemo(() => makeClosedNavCategoriesAtom(userId), [userId]);
 
diff --git a/src/app/pages/client/ClientRoot.tsx b/src/app/pages/client/ClientRoot.tsx
index f4a94fc9..9592ea2c 100644
--- a/src/app/pages/client/ClientRoot.tsx
+++ b/src/app/pages/client/ClientRoot.tsx
@@ -2,11 +2,7 @@ import { Box, Button, config, Dialog, Text } from 'folds';
 import { HttpApiEvent, HttpApiEventHandlerMap, MatrixClient, SyncState } from 'matrix-js-sdk';
 import React, { ReactNode, useCallback, useEffect, useState } from 'react';
 import { useTranslation } from 'react-i18next';
-import {
-  clearLocalSessionAndReload,
-  initClient,
-  startClient,
-} from '../../../client/initMatrix';
+import { clearLocalSessionAndReload, initClient, startClient } from '../../../client/initMatrix';
 import { ServerConfigsLoader } from '../../components/ServerConfigsLoader';
 import { CapabilitiesProvider } from '../../hooks/useCapabilities';
 import { MediaConfigProvider } from '../../hooks/useMediaConfig';
@@ -138,9 +134,15 @@ export function ClientRoot({ children }: ClientRootProps) {
     onRetry = loadMatrix;
   }
 
+  // When `getFallbackSession()` returns `undefined` (no stored session),
+  // `loadMatrix()` throws and the error branch below renders inside
+  // `AuthSplashScreen`. The empty-string defaults reach AutoDiscovery /
+  // SpecVersions but neither component does anything load-bearing with them
+  // in the error path — AutoDiscovery falls back to an empty `m.homeserver`
+  // record, SpecVersions probes the current origin (harmless).
   return (
-    <AutoDiscovery userId={userId!} baseUrl={baseUrl!}>
-      <SpecVersions baseUrl={baseUrl!}>
+    <AutoDiscovery userId={userId ?? ''} baseUrl={baseUrl ?? ''}>
+      <SpecVersions baseUrl={baseUrl ?? ''}>
         {mx && <SyncIndicator mx={mx} />}
         {(loadState.status === AsyncStatus.Error ||
           startState.status === AsyncStatus.Error ||
@@ -168,9 +170,7 @@ export function ClientRoot({ children }: ClientRootProps) {
                   {loading &&
                     syncErrored &&
                     loadState.status !== AsyncStatus.Error &&
-                    startState.status !== AsyncStatus.Error && (
-                      <Text>{t('Boot.sync_failed')}</Text>
-                    )}
+                    startState.status !== AsyncStatus.Error && <Text>{t('Boot.sync_failed')}</Text>}
                   <Button variant="Critical" onClick={onRetry}>
                     <Text as="span" size="B400">
                       {t('Boot.retry')}
diff --git a/src/app/pages/client/direct/RoomProvider.tsx b/src/app/pages/client/direct/RoomProvider.tsx
index 4fa0d894..051aa4c3 100644
--- a/src/app/pages/client/direct/RoomProvider.tsx
+++ b/src/app/pages/client/direct/RoomProvider.tsx
@@ -41,7 +41,8 @@ export function DirectRouteRoomProvider({ children }: { children: ReactNode }) {
   // After P3c the Direct tab is universal — any joined non-space room renders
   // here. Spaces (= future Channels) keep their own /{spaceId}/ route.
   if (!room || isSpace(room)) {
-    return <JoinBeforeNavigate roomIdOrAlias={roomIdOrAlias!} eventId={eventId} />;
+    if (!roomIdOrAlias) return <Navigate to={getDirectPath()} replace />;
+    return <JoinBeforeNavigate roomIdOrAlias={roomIdOrAlias} eventId={eventId} />;
   }
 
   return <ResolvedRoomProvider room={room}>{children}</ResolvedRoomProvider>;
diff --git a/src/app/pages/client/home/RoomProvider.tsx b/src/app/pages/client/home/RoomProvider.tsx
index 1123f909..f101ddd3 100644
--- a/src/app/pages/client/home/RoomProvider.tsx
+++ b/src/app/pages/client/home/RoomProvider.tsx
@@ -43,21 +43,15 @@ export function HomeRouteRoomProvider({ children: _children }: { children: React
     const alias = getCanonicalAliasOrRoomId(mx, room.roomId);
     const orphanParents = getOrphanParents(roomToParents, room.roomId);
     if (orphanParents.length > 0) {
-      const parentSpace =
-        guessPerfectParent(mx, room.roomId, orphanParents) ?? orphanParents[0];
+      const parentSpace = guessPerfectParent(mx, room.roomId, orphanParents) ?? orphanParents[0];
       const pSpaceIdOrAlias = getCanonicalAliasOrRoomId(mx, parentSpace);
-      return (
-        <Navigate to={getChannelsRoomPath(pSpaceIdOrAlias, alias, eventId)} replace />
-      );
+      return <Navigate to={getChannelsRoomPath(pSpaceIdOrAlias, alias, eventId)} replace />;
     }
     return <Navigate to={getDirectRoomPath(alias, eventId)} replace />;
   }
 
+  if (!roomIdOrAlias) return <Navigate to="/direct" replace />;
   return (
-    <JoinBeforeNavigate
-      roomIdOrAlias={roomIdOrAlias!}
-      eventId={eventId}
-      viaServers={viaServers}
-    />
+    <JoinBeforeNavigate roomIdOrAlias={roomIdOrAlias} eventId={eventId} viaServers={viaServers} />
   );
 }
diff --git a/src/app/pages/client/sidebar/SettingsTab.tsx b/src/app/pages/client/sidebar/SettingsTab.tsx
index dc5672a2..dfa38295 100644
--- a/src/app/pages/client/sidebar/SettingsTab.tsx
+++ b/src/app/pages/client/sidebar/SettingsTab.tsx
@@ -4,6 +4,7 @@ import { useMatch, useNavigate } from 'react-router-dom';
 import { SidebarItem, SidebarItemTooltip, SidebarAvatar } from '../../../components/sidebar';
 import { UserAvatar } from '../../../components/user-avatar';
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
+import { useAuthedUserId } from '../../../hooks/useAuthedUserId';
 import { getMxIdLocalPart, mxcUrlToHttp } from '../../../utils/matrix';
 import { nameInitials } from '../../../utils/common';
 import { useMediaAuthentication } from '../../../hooks/useMediaAuthentication';
@@ -17,7 +18,7 @@ export function SettingsTab() {
   const useAuthentication = useMediaAuthentication();
   const navigate = useNavigate();
   const settingsMatch = useMatch({ path: SETTINGS_PATH, caseSensitive: true, end: false });
-  const userId = mx.getUserId()!;
+  const userId = useAuthedUserId();
   const profile = useUserProfile(userId);
 
   const displayName = profile.displayName ?? getMxIdLocalPart(userId) ?? userId;
diff --git a/src/app/pages/client/space/RoomProvider.tsx b/src/app/pages/client/space/RoomProvider.tsx
index 1ea76133..0de21960 100644
--- a/src/app/pages/client/space/RoomProvider.tsx
+++ b/src/app/pages/client/space/RoomProvider.tsx
@@ -1,6 +1,6 @@
 import React, { ReactNode } from 'react';
 import { Room } from 'matrix-js-sdk';
-import { useParams } from 'react-router-dom';
+import { Navigate, useParams } from 'react-router-dom';
 import { useAtom, useAtomValue } from 'jotai';
 import { useSelectedRoom } from '../../../hooks/router/useSelectedRoom';
 import { IsOneOnOneProvider, RoomProvider } from '../../../hooks/useRoom';
@@ -41,12 +41,9 @@ export function SpaceRouteRoomProvider({ children }: { children: ReactNode }) {
 
   if (!room || !allRooms.includes(room.roomId)) {
     // room is not joined
+    if (!roomIdOrAlias) return <Navigate to="/direct" replace />;
     return (
-      <JoinBeforeNavigate
-        roomIdOrAlias={roomIdOrAlias!}
-        eventId={eventId}
-        viaServers={viaServers}
-      />
+      <JoinBeforeNavigate roomIdOrAlias={roomIdOrAlias} eventId={eventId} viaServers={viaServers} />
     );
   }
 
@@ -67,12 +64,9 @@ export function SpaceRouteRoomProvider({ children }: { children: ReactNode }) {
       });
     }
 
+    if (!roomIdOrAlias) return <Navigate to="/direct" replace />;
     return (
-      <JoinBeforeNavigate
-        roomIdOrAlias={roomIdOrAlias!}
-        eventId={eventId}
-        viaServers={viaServers}
-      />
+      <JoinBeforeNavigate roomIdOrAlias={roomIdOrAlias} eventId={eventId} viaServers={viaServers} />
     );
   }
 
diff --git a/src/app/pages/client/space/Space.tsx b/src/app/pages/client/space/Space.tsx
index 44b5a140..6d257a04 100644
--- a/src/app/pages/client/space/Space.tsx
+++ b/src/app/pages/client/space/Space.tsx
@@ -343,7 +343,8 @@ export function SpaceTombstone({ roomId, replacementRoomId }: SpaceTombstoneProp
         <Text size="T200">This space has been replaced and is no longer active.</Text>
         {joinState.status === AsyncStatus.Error && (
           <Text className={BreakWord} style={{ color: color.Critical.Main }} size="T200">
-            {(joinState.error as any)?.message ?? 'Failed to join replacement space!'}
+            {(joinState.error as { message?: string } | undefined)?.message ??
+              'Failed to join replacement space!'}
           </Text>
         )}
       </Box>
diff --git a/src/app/plugins/call/CallEmbed.ts b/src/app/plugins/call/CallEmbed.ts
index 362e6db3..9b618298 100644
--- a/src/app/plugins/call/CallEmbed.ts
+++ b/src/app/plugins/call/CallEmbed.ts
@@ -126,8 +126,15 @@ export class CallEmbed {
     const iframe = document.createElement('iframe');
 
     iframe.title = 'Call Embed';
-    iframe.sandbox =
-      'allow-forms allow-scripts allow-same-origin allow-popups allow-modals allow-downloads';
+    // `HTMLIFrameElement.sandbox` is typed as a `DOMTokenList` in modern
+    // lib.dom; string assignment is rejected by the `--strict` compiler even
+    // though browsers still honour it via `[PutForwards=value]`. Use
+    // `setAttribute` for an unambiguous, strict-typed write. Must be set
+    // BEFORE `iframe.src` so the sandbox policy applies at first navigation.
+    iframe.setAttribute(
+      'sandbox',
+      'allow-forms allow-scripts allow-same-origin allow-popups allow-modals allow-downloads'
+    );
     iframe.allow = 'microphone; camera; display-capture; autoplay; clipboard-write;';
     iframe.src = url;
 
@@ -201,7 +208,7 @@ export class CallEmbed {
     return this.listenEvent('preparing', callback);
   }
 
-  public onPreparingError(callback: (error: any) => void) {
+  public onPreparingError(callback: (error: unknown) => void) {
     return this.listenEvent('error:preparing', callback);
   }
 
@@ -228,7 +235,9 @@ export class CallEmbed {
       const events = room.getLiveTimeline()?.getEvents() || [];
       const roomEvent = events[events.length - 1];
       if (!roomEvent) return; // force later code to think the room is fresh
-      this.readUpToMap[room.roomId] = roomEvent.getId()!;
+      const evtId = roomEvent.getId();
+      if (!evtId) return;
+      this.readUpToMap[room.roomId] = evtId;
     });
 
     // Attach listeners for feeding events - the underlying widget classes handle permissions for us
@@ -296,6 +305,9 @@ export class CallEmbed {
     if (this.call === null) return;
     const raw = ev.getEffectiveEvent();
     this.call.feedStateUpdate(raw as IRoomEvent).catch((e) => {
+      // Element Call widget channel error — surface so a stuck widget is
+      // diagnosable without breaking the call lifecycle.
+      // eslint-disable-next-line no-console
       console.error('Error sending state update to widget: ', e);
     });
   }
@@ -329,7 +341,7 @@ export class CallEmbed {
     const room = this.mx.getRoom(roomId);
     if (room === null) return false;
 
-    const upToEventId = this.readUpToMap[ev.getRoomId()!];
+    const upToEventId = this.readUpToMap[roomId];
     if (!upToEventId) {
       // There's no marker yet; start it at this event
       this.readUpToMap[roomId] = evId;
@@ -402,6 +414,7 @@ export class CallEmbed {
       } else {
         const raw = ev.getEffectiveEvent();
         this.call.feedEvent(raw as IRoomEvent).catch((e) => {
+          // eslint-disable-next-line no-console
           console.error('Error sending event to widget: ', e);
         });
       }
diff --git a/src/app/plugins/react-custom-html-parser.tsx b/src/app/plugins/react-custom-html-parser.tsx
index 961131d9..451acff3 100644
--- a/src/app/plugins/react-custom-html-parser.tsx
+++ b/src/app/plugins/react-custom-html-parser.tsx
@@ -149,7 +149,10 @@ export const renderMatrixMention = (
 
 export const factoryRenderLinkifyWithMention = (
   mentionRender: (href: string) => JSX.Element | undefined
+  // linkifyjs render callback is typed `(ir: IntermediateRepresentation) => any` upstream.
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
 ): OptFn<(ir: IntermediateRepresentation) => any> => {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const render: OptFn<(ir: IntermediateRepresentation) => any> = ({
     tagName,
     attributes,
diff --git a/src/app/utils/ASCIILexicalTable.ts b/src/app/utils/ASCIILexicalTable.ts
index 61b2481a..ced66d45 100644
--- a/src/app/utils/ASCIILexicalTable.ts
+++ b/src/app/utils/ASCIILexicalTable.ts
@@ -36,6 +36,9 @@ export class ASCIILexicalTable {
     this.populateWidthToSize();
 
     if (this.size() > Number.MAX_SAFE_INTEGER) {
+      // Diagnostic for upstream Slate decorator math overflow — extremely
+      // unlikely to fire on real alphabets but worth surfacing to devs.
+      // eslint-disable-next-line no-console
       console.warn(
         `[!] Warning: ASCIILexicalTable size is larger than the Number.MAX_SAFE_INTEGER: ${this.size()} > ${
           Number.MAX_SAFE_INTEGER
diff --git a/src/app/utils/common.ts b/src/app/utils/common.ts
index 6bda2802..17f82849 100644
--- a/src/app/utils/common.ts
+++ b/src/app/utils/common.ts
@@ -57,7 +57,7 @@ export const promiseFulfilledResult = <T>(
   if (settledResult.status === 'fulfilled') return settledResult.value;
   return undefined;
 };
-export const promiseRejectedResult = <T>(settledResult: PromiseSettledResult<T>): any => {
+export const promiseRejectedResult = <T>(settledResult: PromiseSettledResult<T>): unknown => {
   if (settledResult.status === 'rejected') return settledResult.reason;
   return undefined;
 };
diff --git a/src/app/utils/matrix-uia.ts b/src/app/utils/matrix-uia.ts
index 15c5799c..bfb97fd3 100644
--- a/src/app/utils/matrix-uia.ts
+++ b/src/app/utils/matrix-uia.ts
@@ -72,7 +72,10 @@ export const getLoginTermUrl = (params: UIAParams): string | undefined => {
     if (terms.policies === null) return undefined;
     if ('privacy_policy' in terms.policies && typeof terms.policies.privacy_policy === 'object') {
       if (terms.policies.privacy_policy === null) return undefined;
-      const langToPolicy = terms.policies.privacy_policy as Record<string, any>;
+      const langToPolicy = terms.policies.privacy_policy as Record<
+        string,
+        { url?: string } | undefined
+      >;
       const url = langToPolicy.en?.url;
       if (typeof url === 'string') return url;
 
diff --git a/src/app/utils/matrix.ts b/src/app/utils/matrix.ts
index e2c60fa1..1c8f4b01 100644
--- a/src/app/utils/matrix.ts
+++ b/src/app/utils/matrix.ts
@@ -13,6 +13,7 @@ import {
   UploadProgress,
   UploadResponse,
 } from 'matrix-js-sdk';
+import type { AccountDataEvents } from 'matrix-js-sdk';
 import to from 'await-to-js';
 import { IImageInfo, IThumbnailContent, IVideoInfo } from '../../types/matrix/common';
 import { AccountDataEvent } from '../../types/matrix/accountData';
@@ -164,9 +165,10 @@ export const uploadContent = async (
     const mxc = data.content_uri;
     if (mxc) onSuccess(mxc);
     else onError(new MatrixError(data));
-  } catch (e: any) {
-    const error = typeof e?.message === 'string' ? e.message : undefined;
-    const errcode = typeof e?.name === 'string' ? e.message : undefined;
+  } catch (e: unknown) {
+    const err = e as { message?: unknown; name?: unknown };
+    const error = typeof err?.message === 'string' ? err.message : undefined;
+    const errcode = typeof err?.name === 'string' ? err.name : undefined;
     onError(new MatrixError({ error, errcode }));
   }
 };
@@ -184,7 +186,7 @@ export const eventWithShortcode = (ev: MatrixEvent) =>
 // Element's findDMForUser (matrix-react-sdk/src/utils/dm/findDMForUser.ts)
 // including the cross-user fallback scan for stale peer state (PR #10127).
 export const getDMRoomFor = (mx: MatrixClient, userId: string): Room | undefined => {
-  const mDirectsEvent = mx.getAccountData(AccountDataEvent.Direct as any);
+  const mDirectsEvent = mx.getAccountData(AccountDataEvent.Direct as keyof AccountDataEvents);
   const mDirect = (mDirectsEvent?.getContent() ?? {}) as Record<string, string[]>;
 
   const myUserId = mx.getUserId();
@@ -264,7 +266,7 @@ export const addRoomIdToMDirect = (
   userId: string
 ): Promise<void> =>
   enqueueMDirectWrite(mx, async () => {
-    const mDirectsEvent = mx.getAccountData(AccountDataEvent.Direct as any);
+    const mDirectsEvent = mx.getAccountData(AccountDataEvent.Direct as keyof AccountDataEvents);
     let userIdToRoomIds: Record<string, string[]> = {};
 
     if (typeof mDirectsEvent !== 'undefined')
@@ -287,12 +289,12 @@ export const addRoomIdToMDirect = (
     }
     userIdToRoomIds[userId] = roomIds;
 
-    await mx.setAccountData(AccountDataEvent.Direct as any, userIdToRoomIds as any);
+    await mx.setAccountData(AccountDataEvent.Direct as keyof AccountDataEvents, userIdToRoomIds);
   });
 
 export const removeRoomIdFromMDirect = (mx: MatrixClient, roomId: string): Promise<void> =>
   enqueueMDirectWrite(mx, async () => {
-    const mDirectsEvent = mx.getAccountData(AccountDataEvent.Direct as any);
+    const mDirectsEvent = mx.getAccountData(AccountDataEvent.Direct as keyof AccountDataEvents);
     let userIdToRoomIds: Record<string, string[]> = {};
 
     if (typeof mDirectsEvent !== 'undefined')
@@ -306,7 +308,7 @@ export const removeRoomIdFromMDirect = (mx: MatrixClient, roomId: string): Promi
       }
     });
 
-    await mx.setAccountData(AccountDataEvent.Direct as any, userIdToRoomIds as any);
+    await mx.setAccountData(AccountDataEvent.Direct as keyof AccountDataEvents, userIdToRoomIds);
   });
 
 export const mxcUrlToHttp = (
diff --git a/src/app/utils/push.ts b/src/app/utils/push.ts
index 6636c9e7..9de9d04e 100644
--- a/src/app/utils/push.ts
+++ b/src/app/utils/push.ts
@@ -141,7 +141,6 @@ export async function ensureRtcRingPushRule(mx: MatrixClient): Promise<void> {
   }
 }
 
-
 // Symmetric cleanup for `useDisablePushNotifications`. The rules live in
 // account data so they would otherwise outlive the pusher — and other logged-in
 // clients (Element, a second Vojo session) would keep applying the ring
@@ -163,7 +162,6 @@ export async function removeRtcRingPushRule(mx: MatrixClient): Promise<void> {
   }
 }
 
-
 export async function registerWebPusher(
   mx: MatrixClient,
   subscription: PushSubscription,
@@ -193,13 +191,17 @@ export async function registerWebPusher(
       app_display_name: 'Vojo Web',
       device_display_name: navigator.userAgent.slice(0, 120),
       lang: navigator.language || 'en',
+      // SDK's pusher `data` type only declares `{ format?, url?, brand? }`.
+      // Sygnal / UnifiedPush also read `endpoint`, `auth`, `events_only`; the
+      // extra fields are forwarded to the gateway and required for web-push
+      // delivery. Cast through `unknown` to drop the over-narrow SDK shape.
       data: {
         url: gatewayUrl,
         endpoint: subscription.endpoint,
         auth: arrayBufferToBase64Url(auth),
         format: 'event_id_only',
         events_only: true,
-      },
+      } as unknown as { format?: string; url?: string; brand?: string },
       append: true,
     })
   );
diff --git a/src/app/utils/room.ts b/src/app/utils/room.ts
index 03645c44..94dcffa4 100644
--- a/src/app/utils/room.ts
+++ b/src/app/utils/room.ts
@@ -17,6 +17,7 @@ import {
   Room,
   RoomMember,
 } from 'matrix-js-sdk';
+import type { AccountDataEvents } from 'matrix-js-sdk';
 import { CryptoBackend } from 'matrix-js-sdk/lib/common-crypto/CryptoBackend';
 import { AccountDataEvent } from '../../types/matrix/accountData';
 import {
@@ -44,7 +45,7 @@ export const getStateEvents = (room: Room, eventType: StateEvent): MatrixEvent[]
 export const getAccountData = (
   mx: MatrixClient,
   eventType: AccountDataEvent
-): MatrixEvent | undefined => mx.getAccountData(eventType as any);
+): MatrixEvent | undefined => mx.getAccountData(eventType as keyof AccountDataEvents);
 
 export const getMDirects = (mDirectEvent: MatrixEvent): Set<string> => {
   const roomIds = new Set<string>();
diff --git a/src/client/initMatrix.ts b/src/client/initMatrix.ts
index 73f621b7..0d3f67ea 100644
--- a/src/client/initMatrix.ts
+++ b/src/client/initMatrix.ts
@@ -31,6 +31,8 @@ export const initClient = async (session: Session): Promise<MatrixClient> => {
     cryptoStore: legacyCryptoStore,
     deviceId: session.deviceId,
     timelineSupport: true,
+    // cryptoCallbacks ships from a .js module with a duck-typed shape; matrix-js-sdk's exported type is too narrow.
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
     cryptoCallbacks: cryptoCallbacks as any,
     verificationMethods: ['m.sas.v1'],
   });
diff --git a/src/index.tsx b/src/index.tsx
index d3b34941..f37ad150 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -87,6 +87,9 @@ const mountApp = () => {
   const rootContainer = document.getElementById('root');
 
   if (rootContainer === null) {
+    // Bootstrap failure — only surfaces if `index.html` is broken; logging
+    // is the only path here since React hasn't mounted yet.
+    // eslint-disable-next-line no-console
     console.error('Root container element not found!');
     return;
   }
diff --git a/src/sw.ts b/src/sw.ts
index c663d3cc..d9a7d606 100644
--- a/src/sw.ts
+++ b/src/sw.ts
@@ -29,7 +29,7 @@ async function cleanupDeadClients() {
   });
 }
 
-function setSession(clientId: string, accessToken: any, baseUrl: any) {
+function setSession(clientId: string, accessToken: unknown, baseUrl: unknown) {
   if (typeof accessToken === 'string' && typeof baseUrl === 'string') {
     sessions.set(clientId, { accessToken, baseUrl });
   } else {
diff --git a/src/types/matrix/sdkAugmentation.d.ts b/src/types/matrix/sdkAugmentation.d.ts
new file mode 100644
index 00000000..ef39b538
--- /dev/null
+++ b/src/types/matrix/sdkAugmentation.d.ts
@@ -0,0 +1,33 @@
+// Module augmentation: extend matrix-js-sdk's AccountDataEvents and StateEvents
+// interfaces with the custom Matrix event types Vojo / upstream Cinny uses
+// (Vojo spaces sidebar, Ponies emote/sticker packs, Element recent emoji,
+// MSC2346 bridge metadata, MSC3401 group-call membership, MSC4143 RTC member,
+// Vojo power-level tags). Without this, `mx.getAccountData(<custom-key>)` /
+// `mx.getStateEvent(<custom-key>)` / `state.getStateEvents(<custom-key>)` fail
+// `keyof XxxEvents` narrowing in TypeScript 5.4+.
+//
+// Content types stay `unknown` here on purpose — call sites already invoke
+// `.getContent<T>()` with the right local content type. Keep this file dep-free
+// (only ambient declarations) so it loads before any value imports.
+
+import 'matrix-js-sdk';
+
+declare module 'matrix-js-sdk' {
+  // eslint-disable-next-line @typescript-eslint/no-empty-interface, @typescript-eslint/consistent-type-definitions
+  interface AccountDataEvents {
+    'in.vojo.spaces': unknown;
+    'io.element.recent_emoji': unknown;
+    'im.ponies.user_emotes': unknown;
+    'im.ponies.emote_rooms': unknown;
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-empty-interface, @typescript-eslint/consistent-type-definitions
+  interface StateEvents {
+    'im.ponies.room_emotes': unknown;
+    'in.vojo.room.power_level_tags': unknown;
+    // MSC2346 bridge metadata — stable + unstable variants. Mautrix-* and
+    // similar bridges write at least one; SDK ships no built-in typing.
+    'm.bridge': unknown;
+    'uk.half-shot.bridge': unknown;
+  }
+}