perf(web): resume syntax highlighting from completed lines - #11196

## What's Changed
* fix(pr): update labels and reviewers without redundant reloads by @maria-rcks in pingdotgg/t3code#11117
* fix(chat): fold question answers into tool activity by @maria-rcks in pingdotgg/t3code#11014
* fix(usage): flag unpriced model activity instead of showing $0.00 by @maria-rcks in pingdotgg/t3code#11021
* fix(server): let Claude launch args override the derived permission mode by @maria-rcks in pingdotgg/t3code#11026
* fix(editors): accept root paths and Windows servers in Zed remote links by @maria-rcks in pingdotgg/t3code#11044
* fix(web): center pull request unavailable states by @maria-rcks in pingdotgg/t3code#11110
* fix(web): remove sidebar pull request link icon by @maria-rcks in pingdotgg/t3code#11179
* fix(ui): color linked pr counts by aggregate status by @maria-rcks in pingdotgg/t3code#11180
* fix(preview): render website favicons for browser tool activity by @maria-rcks in pingdotgg/t3code#11032
* fix(web): simplify pull request summary sections by @maria-rcks in pingdotgg/t3code#10612
* fix(web): preserve drafts when compacting context by @maria-rcks in pingdotgg/t3code#11103
* fix(server): queue messages during context compaction by @maria-rcks in pingdotgg/t3code#11107
* perf(web): format minimap previews only when opened by @juliusmarminge in pingdotgg/t3code#11181
* perf(web): reuse completed Markdown prefixes while streaming by @juliusmarminge in pingdotgg/t3code#11193
* perf(web): resume syntax highlighting from completed lines by @juliusmarminge in pingdotgg/t3code#11196
* perf(web): preserve completed code-line DOM while streaming by @juliusmarminge in pingdotgg/t3code#11198
* perf(web): huge-thread switch no longer blanks the chat pane by @juliusmarminge in pingdotgg/t3code#11169


**Full Changelog**: pingdotgg/t3code@v0.0.41-nightly.20260911.1520...v0.0.41-nightly.20260911.1533

Upstream release: https://github.com/pingdotgg/t3code/releases/tag/v0.0.41-nightly.20260911.1533

…#11196)

Merges `upstream/main` at `e81606494` into the fork, from merge base
`02297e3db` — 47 upstream commits.

The theme of this range is scopable settings: upstream made every server
setting addressable at a scope (global / environment / project) with
per-project overrides, which is why 11 of the 15 conflicts are settings
files. The rest is conversation rewind, floating device streams, and a
large batch of message-sync and markdown-streaming perf work.

## Merge stats

- Landed (`HEAD^1..HEAD`): 277 files, 17243+/4783−
- Upstream range (base..`HEAD^2`): 275 files, 17011+/4749−
- Fork delta (`HEAD^2..HEAD`): 756 files, 76559+/2096−

The two file lists reconcile: the 3 extra landed files are
`docs/fork/inventory.json`, `docs/fork/upstream-merge-log.md` and
`docs/fork/gaps.md`; the 1 file in the range that did not land is
`apps/web/src/routes/settings.integrations.tsx`, resolved `ours` per the
`moatless-admin-integrations-route` inventory entry (that route is a
Moatless admin page here, and upstream's embedded-surface settings live
at `/settings/browser`).

All 15 conflicts were resolved by the verdict `preflight.mjs` printed.
No `decide` conflict was left unresolved. Details, including the
owned-concern sweep (no keyword hits) and the unsupported-method
reconciliation (0 ADD, 0 DROP, 2 KEEP, 4 known exceptions), are in the
dated entry in `docs/fork/upstream-merge-log.md`.

Two findings worth naming here:

- **A silent auto-merge failure.** pingdotgg#11285 changed the mini-player target
from a tab id to a source union. Git updated upstream's own assertion in
`PreviewView.test.tsx` and left the fork-only "under the frame
capability" case next to it still asserting the old string. No conflict
marker, no `resolution-check.mjs` finding — only the fork's own test
suite caught it.
- **Stale inventory anchors.** Upstream moved the project Actions
section out of `ProjectSettingsPanel.tsx` into a new
`ProjectActionsSettings.tsx`, which is where `scriptsEditable` is now
derived and where upstream's new writing Reset button is gated. Four
inventory entries were re-pointed in this merge rather than silently
dropping their deltas.

## Usable as-is

Client work the fork can expose with no Moatless backend change:

- Scoped settings UI and the two-select scope picker (pingdotgg#10639, pingdotgg#10636) —
`SettingsScopeContext`, `ScopedSwitch`, `settingKeys`, the `mixed`
state. The reading half works against Moatless today.
- Float device streams over chat, as a source union rather than a tab id
(pingdotgg#11285); recording status on floating previews (pingdotgg#11312); floating
preview using composer margins (pingdotgg#11290).
- PR-page selections into new drafts (pingdotgg#11296);
projects-on-another-machine badge (pingdotgg#11323); Usage opening on Limits
(pingdotgg#11261).
- macOS permission onboarding (pingdotgg#11289); hold-to-quit fix (pingdotgg#11016);
preview keystrokes kept out of the composer (pingdotgg#11354).
- Message-sync and markdown-streaming perf: pingdotgg#11302, pingdotgg#11029, pingdotgg#11211,
pingdotgg#11198, pingdotgg#11196, pingdotgg#11193, pingdotgg#11181, pingdotgg#11206.
- Assorted web/mobile fixes: pingdotgg#11361, pingdotgg#10757, pingdotgg#11357, pingdotgg#10571, pingdotgg#11348,
pingdotgg#11349, pingdotgg#11281, pingdotgg#11188, pingdotgg#11283, pingdotgg#11292, pingdotgg#11187, pingdotgg#11228, pingdotgg#11103, pingdotgg#10612,
pingdotgg#11032, pingdotgg#11233, pingdotgg#11234, pingdotgg#11304, pingdotgg#11240.

## Unsupported in Moatless / needs implementation

- **Conversation rewind** — `thread.conversation.revert` (pingdotgg#11358). A new
member of `DispatchableClientOrchestrationCommand` in
`packages/contracts/src/orchestration.ts`, bringing the fork to 30
command types (28 upstream's, 2 fork-only). Moatless does not dispatch
it, and a client command cannot be refused per-type, so "Edit from here"
on `RevertUserMessageButton` is reachable whenever the turn is idle and
does nothing. Needs backend dispatch.
- **Per-project setting overrides** — the `projectSettingsOverrides`
capability and the 17-key `ProjectSettingsOverrides` record (pingdotgg#11176).
Two pieces are needed: the capability reported by
`/.well-known/t3/environment`, and `server.updateSettings` served at
project scope. Until both land, the capability filter in
`scopedSettings.ts:170` and `ProjectActionsSettings.tsx:72` drops the
write on the client — the control renders, the user toggles it, and
**the write never leaves the browser**. A silent no-op is worse than a
hidden control or an honest refusal; recorded in `docs/fork/gaps.md`.
- **Default thread permissions** — `defaultRuntimeMode` (pingdotgg#11346). Reads
fine, cannot be saved. Same `server.updateSettings` write path as above,
one level deeper, not a separate gap.

## Backend behavior to consider reproducing in Moatless

Upstream server-side work the fork cannot use directly, but that
Moatless would benefit from:

- **Queue messages during context compaction** (pingdotgg#11107,
`ProviderCommandReactor.ts`) — a message sent while compaction is in
flight is currently dropped rather than held.
- **Restore provider history and prompts when rewinding** (pingdotgg#11338,
`CheckpointReactor.ts`) — the counterpart to
`thread.conversation.revert` above; rewinding the thread without
rewinding provider state leaves the two out of sync.
- **Detect file renames in review diffs** (pingdotgg#8086,
`apps/server/src/vcs/GitVcsDriverCore.ts`) — a rename currently reads as
a whole-file delete plus a whole-file add.
- **Preserve qualified Codex model ids** (pingdotgg#9921, `ModelManifest.ts` +
`CodexTextGeneration.ts`).
- **Model defaults** astra-medium / fable-5.1-medium (pingdotgg#11347).

All five are recorded under the runtime-fixes entry in
`docs/fork/gaps.md`.

## Verification

`verify.mjs` (full pass): 7 of 8 checks green — `duplicate-adds`,
`tripwires`, `resolution-check`, `unsupported-methods`, `fmt:check`,
`lint`, `typecheck`.

`test` is red on **`@t3tools/desktop` only**, at
`scripts/browser-secret-native.test.mjs > bundled libsecret helper`:
`Command failed: pkg-config --cflags --libs libsecret-1`. This is the
standing sandbox gap, not a merge regression — the test file's last
commit is `498ab9c39` (pingdotgg#7261, before the merge base), `git diff
--name-only` against both merge parents is empty for it, and `pkg-config
--exists libsecret-1` fails in this environment. It is already an entry
in `docs/fork/gaps.md`. Every other package passes, including
`@t3tools/web` (5079 tests) after the `PreviewView.test.tsx` fix above.

Three typecheck failures the merge introduced were fixed in it:
`SETTINGS_CATEGORY_SCOPES` in `settingsSearch.ts` was missing all 9
fork-only settings paths, and two `filterAvailableSettingsSearchItems`
literals in `settingsSearch.test.ts` were missing the fork's
`forgejoEnabled` field.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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Moatless task:
https://moatless.soaplabstest.com/tasks/e70b41b3-779d-43b8-8f34-7de516548e7c