[saphid]

The Files explorer and single-file view move onto the shared typed panel registry and host, so the launcher and panel mount use the same definition. The intended visible behavior stays the same.

Review scope: this PR targets main. Its full contribution includes the panel registry/host and earlier Browser, Diff, Terminal, Device and pull-request migrations, as well as Files; review the full base-to-head range rather than only the historical Files commit. Related earlier layers are #16038, #16039, #16040, #16041 and #16042. The architecture direction in discussion #14938 still needs a maintainer decision; this PR remains open pending that decision.

Problem

The Files explorer and single-file view are the last right-panel body still mounted by hand in ChatView, with its own lazy import, Suspense wrapper and a file-open callback, and the + menu and empty launcher keep a hand-written "Files" row with its own letter, icon and copy, separate from the registered Browser, Diff, Terminal, Device and pull request panels. This PR opens Files as a registered right panel on the panel host, with no visible change.

Why this qualifies

This continues the panel host proposed in Ideas discussion #14938. Files as a right-panel tab is the example CONTRIBUTING gives of a change that needs product approval first, so this PR needs both: agreement on #14938 and product approval of Files as a panel-host tab. No maintainer has agreed to either yet. It is stacked on the pull request panels PR (and through it on the Device, terminal and Preview panel PRs and #15010) and depends on them; review those first. If #14938 is declined, close this too. Previous PR in this stack: refactor(web): open the pull request side panels through the panel host (#16042).

It is a move only. Two existing behaviours of the Files panel are not changed here, though the panel host's rules would forbid them: a desktop tree "Add to chat" whose menu settles after you switch threads inserts into the composer you are now looking at, and an "Open in browser" that settles after you leave still opens a Browser tab in the thread it started in. Both exist on main today; the next PR in this stack fixes them.

Fix

The Files layer moves the existing body and launcher metadata. The complete contribution against main also includes the earlier panel migrations described above.

• panels/bundledPanels.tsx registers files (title "Files", Files icon, letter F, the existing hint and reason) with a lazy load. One definition renders both the Files explorer and every file:<path> surface, as the one component did before; file tabs keep their basename title and file-type icon.
• components/files/FilePreviewPanel.tsx moves to panels/files/FilesSidePanel.tsx. It reads the thread, environment, composer draft target and workspace mutation id from the host, keybindings from the same server atom ChatView used, and opens files into the host thread's right panel. Surface inputs (path, attachment, reveal line), available editors and the pending-save pair stay props, computed in ChatView as before.
• ChatView mounts <RegisteredSidePanel id="files" …/> under the same condition and key, so explorer state still carries across Files and file tabs in a project, and passes the existing availability and open callback through the panel launcher map.
• RightPanelTabs: the hand-written row becomes registered("files") in the same slot (B T F D P L M); the Files tab title and icon read the definition; two dedicated props are removed. The /pull-requests page lists Files as unavailable, as before.
• Two launcher test fixtures from the earlier panel PRs pass files in the panel map instead of the removed props.
• The Files migration adds no panel-host API, contract, server, desktop or mobile change beyond the earlier layers in the full contribution. Files keeps no loading placeholder while its code loads, exactly as before: ChatView already loaded it lazily with an empty fallback.

Current verification

At 5bf4f23:

• Migrated all seven remaining react-test-renderer suites to React DOM, and placed those plus the existing DOM suites in the compiled Chromium project (*.browser.test.tsx). Registry type fixtures, lazy-body loading, host/environment switches, Files breadcrumb navigation and pull-request actions retain behavioral assertions.
• Fixed the terminal transport mock’s accidental then method, which caused promise assimilation to hang. Device cleanup uses promise callbacks instead of the compiler-unsupported try/finally, preserving pending-state cleanup and thread scoping.
• tsc-rs --noEmit -p apps/web/tsconfig.json: passed. Targeted vp lint on all 12 changed files: exit 0, with one existing array-index-key warning in the linked-list test stub. vp fmt --check on those files and git diff --check: passed.
• Local compiler-enabled jsdom fallback: 11 files / 31 tests passed. This excludes the browser-profile interaction case. Scratch-only getAnimations and scrollIntoView shims supply browser APIs absent in jsdom; the initial Files run failed two cases because scrollIntoView was missing. No production code was changed for those missing APIs.
• Actual vp test run --project browser could not load config locally because installed dependencies lack @vitest/browser-playwright. No dependencies were installed. The fallback is not Chromium verification. Current-head CI is complete but blocked: Test Web aborts with an unhandled Vitest mock-factory rejection; the nested cause repeats the same wrapper and names no underlying exception or module. Aggregate Check fails as a result. Build and Typecheck, Lint, Test and all eight server shards pass. The missing local browser provider prevents a matching focused Chromium reproduction; no dependency install, speculative source fix or CI retry was attempted in this follow-up. A focused run in an equipped Chromium environment that exposes the underlying mock exception is still needed. On parent 1986ba1, Build and Typecheck, Test Web and aggregate Check failed despite the seven-required-check summary.
• Fresh independent review was skipped under the recovery instruction forbidding delegates. The known staged hook is unavailable in the non-Git source fixture; focused lint/format ran directly. No new client captures were made for this compatibility repair.
• CodeRabbit’s summary reports low merge risk through ebb72ea, which does not establish review of the current head. It retains a possible open-panel rendering cost and the missing maintainer/product approvals. No new current-head code finding was posted in this update. Macroscope still requires human approval for the full panel architecture.
• The older host-value memoization request was withdrawn after comparison with the previous prop path. The older terminal strict-subset finding was previously verified as existing behavior in main’s terminal path, as explained in the existing source-backed reply; it was not changed in this repair. Macroscope now explicitly marks that finding no longer relevant as of the current head.

Historical evidence

The following captures and measurements apply to their named earlier revisions. They are not fresh client verification of the full current diff. Earlier recorded local verification at d1554f5 reported 35 files / 418 tests, web typecheck, targeted lint/format and knip passing; those checks were not repeated as that historical range in this follow-up.

Environment: macOS arm64. Before = the pull request panels PR head eb0fc75cc8; after = the earlier candidate 619713c985. Both revisions ran in turn from one checkout on the same fresh isolated state (no copied user data). Two synthetic git projects: alpha (nested src/lib/deep, a 70-line util.ts, Markdown, public/page.html) and beta. Thread A in alpha holds a util.ts:42 link, a text and an HTML attachment, and agent turns that append a line to util.ts; thread B is in beta. Agent turns used Codex with existing CLI auth. Owned Playwright Chromium at 1440×900, dark and light. Built Electron (vp run build:desktop, rc 0 on both revisions) with an owned profile against the same isolated server. Captures by GPT-6 Astra; every image was inspected by Claude Opus 5.5.

Repro: open thread A, open Files from the + menu or empty launcher (click or F), expand src/lib/deep, open files from the tree, breadcrumbs, palette file picker (Cmd+P), content search (Cmd+Shift+F), the util.ts · L42 link and an attachment; comment on line 42; switch to thread B and back; close and collapse the panel and reopen; ask the agent to append a line to the open util.ts.

Observed: no visible difference between before and after at any step. The menu, launcher, tab strip, tree, breadcrumbs, file tabs (basename + file-type icon), line-42 reveal (re-revealed on a second click), attachment preview, line comments, desktop tree "Add to chat", and the automatic refresh after an agent edit look and behave the same.

Flow (web, dark, real time excerpts):

Before (the pull request panels PR):

After (this PR):

MP4s: excerpts before / after; full recordings before / after.

+ menu (Files on F) and empty launcher:

Before:

After:

Before:

After:

File tab from the util.ts · L42 link (line revealed), tree expanded:

Before:

After:

Light theme, Files tree and file tab:

Before:

After:

Before:

After:

Built Electron, dark and light:

Before, dark:

After, dark:

Before, light:

After, light:

More states: breadcrumbs, attachment, comment, tree "Add to chat", Browser, refresh, thread switch

Breadcrumb dropdown — before, after.
Content search to line 42 — before, after.
Attachment preview (no tree or breadcrumbs) — dark before / after, light before / after.
Line comment lands in thread A's composer — before, after.
Open in editor picker — before, after.
Electron tree "Add to chat" — before, after.
Electron workspace HTML → Browser tab in the same thread — before, after.
Refresh after an agent edit — before: pre → refreshed; after: pre → refreshed.
Thread B — before, after.

Explorer state, same script on both revisions (each run twice, identical):

Step	Before	After
Expand src/lib/deep from the launcher's Files	expanded	expanded
Click util.ts in the tree	replaces the Files tab with util.ts	same
+ → Files again	src/lib/deep still expanded	same
Right-panel toggle closed then open	Files active, tree back at root	same
Close Files (×) with util.ts open, reopen from +	expansion kept	same
A → B → A	B shows its own files; A's Files tab active, tree back at root	same

Recordings: before, after. Checkpoint stills web-dark-<before|after>-r2-s{0..4}-*.png in the same folder.

Cold first open (server restarted, empty-cache browser, click Files in the empty launcher; DOM timeline from the click): both revisions show a blank panel while the Files code loads, then the body with "Loading files…" briefly, then the tree. Body appeared at 513 ms before / 434 ms after; under Fast 3G 3916 / 3915 ms, label for 61 / 68 ms. Single samples, not a benchmark. Fast 3G clips: before, after.

Without a project: "or start without a project" opens a "No project" thread backed by a managed Scratch workspace, so Files is available and opens an empty tree on both revisions (before, after; light before / after).

Remote browser (vp run dev --share, after only): an owned isolated server's own pairing link in a fresh unpaired Chromium on a non-loopback HTTPS origin. On first load the dev splash showed for about 15 s before the app appeared; a follow-up comparison of the parent and this PR (7 runs, cold and warm, also over loopback) showed the same splash on both and no reload needed. After that, browsing the tree, opening util.ts, an agent edit refreshing the open file automatically, and a page reload (tab and latest line kept) all worked.

Also: browse, open, reload.

Historical checks at 619713c985, re-run 2026-10-05 (CI=true, all exit 0):

• vp test run src/panels src/components/RightPanelTabs.test.tsx src/components/RightPanelTabs.terminal.test.tsx src/components/RightPanelTabs.browserProfile.test.tsx src/components/files src/components/device src/rightPanelStore.test.ts src/components/ChatView.logic.test.ts (apps/web): 35 files, 386 tests pass. Recorded during development, with this PR's source reverted to its parent, the Files panel suite cannot load; with only the registration reverted, both of its tests fail (Unknown panel id: files).
• The new Files panel suite renders through the registry into the real Files body and breadcrumbs, with hosts that share a thread id across two environments: the breadcrumb folder lists the host environment's files, and picking one opens it as a tab in the host thread only; moving the same mounted panel to the other environment's thread lists and opens there instead. Reading the thread once, capturing the environment at first render, or opening into a fixed environment each fails a test.
• vp run --filter @t3tools/web typecheck passes; compile-only fixtures (Files without its surface inputs, Files props on Preview, host-owned draft target as a prop) and the new suite produce 9 type errors against the parent.
• vp lint --report-unused-disable-directives and vp fmt --check on the touched files: pass; lint warnings equal the parent's. vp run knip:check passes.
• Not part of the re-run: vp run --filter @t3tools/web build passed when this PR was built; the Files body (192 kB) stays its own lazy chunk, now loaded by the registry instead of ChatView. The web build, vp run build:desktop and node scripts/release-smoke.ts passed at the top of this stack (the example plugins PR), which contains this change.

Surfaces

• Entry points: the + menu and empty launcher (click and F) open the Files tab; the tab strip shows it. The command palette has no command that opens the Files tab, before or after; its file picker and project search open file tabs, which this body renders, unchanged. There is no keybinding that opens the Files tab; the file picker keybinding and the right-panel toggle/close/maximize keybindings are unchanged. In the chat, file links, attachments, composer mentions and diff "open file" open file tabs as before. This PR adds no entry point.
• Web: affected (the only code changed).
• Desktop: wraps the same web bundle; Electron shell, preload, IPC and CSP are unchanged. Native tree context menus and open-in-browser keep their existing paths.
• Mobile: not affected. Mobile does not import apps/web and has no Files right panel.
• Providers (Codex, Claude, Cursor, Grok, OpenCode, Antigravity): not affected; Files is provider-independent.
• Contracts: none changed. No wire change.
• Reverse states: none added; open/close/reopen and collapse are the existing paths.
• Local / remote-relay / tunnel: no transport change; file listings, reads and asset URLs use the same environment-scoped paths. A --share remote-browser pass (Evidence) browsed, opened and refreshed files over the wire.
• Docs: none. How to open and use Files does not change.

Not verified

• The "Available when a project is open." hint and its tooltip: no real client state reaches them. A thread started without a project gets a managed Scratch workspace, so Files is available there on both revisions; the unavailable launcher row is covered by the RightPanelTabs tests only.
• File attachments have no Open in editor or Open in browser action on either revision; those controls were exercised on workspace files instead (editor picker shown, not launched; workspace HTML opened a Browser tab in the same thread on Electron).
• Relay and tunnel connections; the remote pass covered --share only, on the after revision. One early run's first page load stayed blank until a reload. A later parent-vs-PR comparison did not reproduce that on either revision; both show the same ~15 s dev-mode splash, so this PR does not cause it.
• Mobile (not affected) and iOS/Android captures; not applicable.
• The Pierre file tree is stubbed in the tests; tree behaviour is covered by the captures above.
• Late desktop tree "Add to chat" and late "Open in browser" behave as on main (see Why this qualifies); fixed in the follow-up PR, not here.
• Release Smoke was not run for this PR (no desktop, server or packaging change); vp run build:desktop passed on both revisions for the captures.

Claude Opus 5.5 (build), GPT-6.1 Sol (review) and GPT-6 Astra (captures) via T3 Code
🤖 Generated with Claude Code

Current compatibility repair and focused verification: GPT-6.1 Sol (high), Codex harness in T3 Code.

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — This PR performs a cross-cutting web architecture migration by introducing a shared panel registry/host and routing all existing side panels through it. Despite preserving intended UI behavior and adding extensive tests, the changes affect common mounting, lazy loading, lifecycle, and thread-context behavior across production paths.

Notes:

• No code objects were reviewed. Approvability was decided on eligibility alone.

^{You can add or adjust custom eligibility rules. Learn more.}

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📝 Walkthrough

The right-panel system now registers seven lazy-loaded panels and uses registry metadata for launcher actions. ChatView provides thread-scoped host state to registered panels. Terminal drawer logic moved into dedicated components, and tests cover registry behavior, launchers, and panel scope changes.

Changes: Registered side-panel system

Layer / File(s)	Summary
Panel registry and bundled definitions apps/web/src/panels/panelRegistry.ts, apps/web/src/panels/panelRegistry.test.tsx, apps/web/src/panels/bundledPanels.tsx, apps/web/src/panels/bundledPanels.test.tsx	Added a typed registry and lazy loading for seven bundled panels. Panel metadata and ID-specific props are defined, with tests for loading, lifecycle, and prop validation.
Metadata-driven panel launchers apps/web/src/components/RightPanelTabs.tsx, apps/web/src/components/RightPanelTabs*.test.tsx, apps/web/src/routes/_chat.pull-requests.tsx	Launcher actions, labels, icons, and availability messages now use panel metadata. The route supplies an unavailable-panel map. Tests cover launcher actions and browser profile selection.
Panel host and ChatView integration apps/web/src/panels/panelHost.ts, apps/web/src/components/ChatView.tsx	ChatView renders registered panels with host context and supplies launcher callbacks to inline and sheet layouts.
Thread-scoped panel implementations apps/web/src/panels/{preview,device,files,pullRequest}/*, apps/web/src/components/preview/PreviewPanel.tsx	Panel implementations use host thread and environment state. Device operations ignore stale results after host scope changes. Tests cover panel actions, scope changes, and capability states.
Terminal panel and persistent drawer apps/web/src/panels/terminal/*, apps/web/src/components/ChatView.tsx	Terminal drawer behavior moved out of ChatView. The terminal panel derives launch data from thread and session state; tests cover attachment, thread changes, and launcher behavior.
Diff panel frame and loading imports apps/web/src/panels/diff/DiffSidePanel.tsx, apps/web/src/components/diffs/*, apps/web/src/components/pullRequest/PullRequest{CodeTab,DetailPanel}.tsx	DiffSidePanel now reads host state and uses an embedded frame. Loading components and pull-request panel imports use DiffLoadingState.

Priority: ⬇️ Low

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Refactor

Merge Risk: 🔵 Low · up to ebb72

This change moves the side panels onto a shared registry and host with no visible behavior change. The remaining concern is extra re-rendering of open panels while ChatView updates. It is a performance cleanup that can be handled during or soon after merge.

Security Architecture Review

Security architecture risk: 🔵 Low · up to ebb72

The reviewed paths preserve existing access scope and do not demonstrate broader privileges. The shared-context change warrants architectural review, but incomplete security coverage limits assurance.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The security-relevant scope remains the selected environment’s workspace operations, terminal execution, device operations, and originating composer context. Shared context makes these capabilities available to trusted bundled implementations, but the reviewed loading and identity paths do not demonstrate new external callers or increased authority.

Trust Boundaries and Controls

• observed — PanelHost is an internal React context carrying existing application capabilities, not an authentication boundary or plugin sandbox. Fixed bundled loaders constrain which implementations receive it; the provider requirement detects missing composition context rather than authorizing remote operations.

Resilience and Maintainability Implications

• observed — Device now resets operation state on a scoped-thread change and binds asynchronous completion handling to a committed-scope token. Navigation, unmounting, or leaving and returning to the same thread invalidates that token, preventing stale results from changing the current panel. This guards UI ownership; it does not cancel or roll back an already issued device operation.

Pre-merge checks: 3 · 2

Failed checks: 2 warnings

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 35.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 60 functions across 31 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Linked Issues check		The description links the relevant discussion and related PRs, but it explicitly states that the required maintainer agreement and product approval are missing.	Add a link to explicit maintainer approval for the panel-host direction and Files as a panel tab, including the approving comment.

Passed checks: 3 passed

Check name	Status	Explanation
Out of Scope Changes check		The broader panel registry and host changes are related dependencies for migrating Files and are documented as part of the full base-to-head contribution. No unrelated change is evident.
Title check		The title clearly and concisely describes the main change: routing the Files side panel through the panel host.
Description check		The description covers the problem, implementation, scope and approval status, verification results, limitations, and affected surfaces. It also clearly discloses that maintainer approval is pending a…

Full details: Description check

Explanation

The description covers the problem, implementation, scope and approval status, verification results, limitations, and affected surfaces. It also clearly discloses that maintainer approval is pending and that matching Chromium verification is blocked.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at @apps/web/src/components/ChatView.tsx:
- Around line 10012-10026: Memoize the PanelHost value so consumers are not
updated when its inputs are unchanged, and keep sendAnnotation stable. Preserve
late-pick behavior by ensuring the callback sends through the sender associated
with the originating activeThreadRef, rather than a sender from a later render.

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📥 Commits

Reviewing files that changed from the base of the PR and between 7812230 and ebb72ea.

📒 Files selected for processing (32)

• apps/web/src/components/ChatView.tsx
• apps/web/src/components/RightPanelTabs.browserProfile.test.tsx
• apps/web/src/components/RightPanelTabs.terminal.test.tsx
• apps/web/src/components/RightPanelTabs.test.tsx
• apps/web/src/components/RightPanelTabs.tsx
• apps/web/src/components/diffs/DiffFileLoadingBoundary.tsx
• apps/web/src/components/diffs/DiffLoadingState.tsx
• apps/web/src/components/preview/PreviewPanel.tsx
• apps/web/src/components/pullRequest/PullRequestCodeTab.tsx
• apps/web/src/components/pullRequest/PullRequestDetailPanel.tsx
• apps/web/src/panels/bundledPanels.test.tsx
• apps/web/src/panels/bundledPanels.tsx
• apps/web/src/panels/device/DeviceSidePanel.test.tsx
• apps/web/src/panels/device/DeviceSidePanel.tsx
• apps/web/src/panels/diff/DiffSidePanel.tsx
• apps/web/src/panels/files/FilesSidePanel.test.tsx
• apps/web/src/panels/files/FilesSidePanel.tsx
• apps/web/src/panels/panelHost.ts
• apps/web/src/panels/panelRegistry.test.tsx
• apps/web/src/panels/panelRegistry.ts
• apps/web/src/panels/preview/PreviewSidePanel.test.tsx
• apps/web/src/panels/preview/PreviewSidePanel.tsx
• apps/web/src/panels/pullRequest/PullRequestPanelPending.tsx
• apps/web/src/panels/pullRequest/PullRequestSidePanel.test.tsx
• apps/web/src/panels/pullRequest/PullRequestSidePanel.tsx
• apps/web/src/panels/pullRequest/PullRequestsSidePanel.test.tsx
• apps/web/src/panels/pullRequest/PullRequestsSidePanel.tsx
• apps/web/src/panels/terminal/PersistentThreadTerminalDrawer.tsx
• apps/web/src/panels/terminal/TerminalSidePanel.attach.test.tsx
• apps/web/src/panels/terminal/TerminalSidePanel.test.tsx
• apps/web/src/panels/terminal/TerminalSidePanel.tsx
• apps/web/src/routes/_chat.pull-requests.tsx

💤 Files with no reviewable changes (1)

• apps/web/src/components/preview/PreviewPanel.tsx

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[saphid]

Review requested

Date (UTC)	Reviewer	Where
2026-10-06	Maria	Discord DM

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