refactor(desktop): own context compaction in Conversation

[chihumyum]

Summary

Refs #4582 — M2, fourth item (context compaction). Landmarks wait for #5712, which rewrites their new home; interaction consumers move with M3.

AppShell currently owns context compaction: it builds the presentation that tracks running notices per Turn, calls window.maka.sessions.compact for /compact, and threads the Host's terminal contextCompactionOutcome back into ConversationLifecycle as a prop. This moves all three into the Conversation owner.

• The Conversation controller creates the one presentation. compactSession calls the injected sessions.compact service, and ConversationLifecycle hands the terminal outcome to the same presentation. A reply that arrives after the Host has settled its Turn still adds nothing.
• AppShell keeps only the stable compactSession command, forwarded to composer submission's /compact port until M3 moves submission; the Conversation README records it as a transitional capability. The shell loses the presentation, the bridge call, the lifecycle prop and its session-workspace-errors import.
• app-shell-context-compaction.ts becomes the private features/conversation/model/context-compaction.ts, sealed by featurePrivateModules; tests reach it through testing.ts. Its copy stays in locales/shell-copy.
• The workspace-unavailable classifier moves to application/contracts/session-workspace-errors.ts. The legacy helper re-exports it, so its four legacy callers are unchanged.

AppShell goes from 9 to 8 bridge paths, 53 to 51 import declarations and 9,614 to 9,385 tokens, and one legacy renderer file is retired. The hook inventory is unchanged (28 hooks / 43 calls). No copy, IPC, storage or visual change.

Verification

• Desktop 3,100/3,100 on Node 24.
• New conversation-compaction.test.ts: command and outcome share the running notice, a finished failure is refused and shown against its Session, a rejected request is reported (workspace-unavailable and generic) only while its Session is current, and each notice uses the locale current when it is shown. A production-owner test drives /compact and the Host outcome through ConversationProvider and ConversationLifecycle. Mutations: dropping the lifecycle hand-off fails the owner test; giving the outcome its own presentation fails three tests.
• e2e/slash-command-compact.spec.ts passes against a local build (Electron, fake backend).
• Renderer architecture fixtures 121/121; --strict-base against c838e1fa7 and the AppShell hook gate pass.
• Typecheck (preload, main, renderer, Storybook), lint, format, Desktop Knip, ASF headers, locale hygiene, E2E budget and build:renderer pass.

Test support: fake-dom.ts gains a querySelector that returns null; Astryx toast dismissal only uses it to decide whether focus must move.

Overlap: conversation-owner.test.ts drops the lifecycle prop on the line next to #5712's harness edit, a one-line resolution for whichever lands second.

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Claude Code implemented this ownership migration, its tests, documentation and validation under human direction. The commit includes Generated-by: Claude Code. This PR awaits independent human review.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

[hqhq1025]

Reviewed commit 769dcebf43e77b86b79c8f3eca5d034ebf51a776. This moves /compact request handling and the shared running/terminal notice into the persistent Conversation owner (apps/desktop/src/renderer/features/conversation/controller/use-conversation-controller.ts:57-64; apps/desktop/src/renderer/features/conversation/model/context-compaction.ts:145-188). The lifecycle now routes Host completion events to that same owner's command (apps/desktop/src/renderer/features/conversation/ui/conversation-lifecycle.tsx:93-99), while AppShell retains only the submit port. Workspace-unavailable classification is moved to an application contract without changing its predicate. I found no substantiated P0-P3 issue in the inspected paths.

Node 24 full build:test, 16 focused Desktop tests, Desktop typecheck, and the renderer architecture check (121 fixtures plus ledger) passed locally. Fetched main c838e1fa merges cleanly and git diff --check passed. The hosted label check is green, but test remains in progress, so the current-head CI gate is not yet established. I did not run the Electron /compact journey, a live Host compaction, or the full local test suite.

Automated review notice: This comment was posted by an automated review agent operated by hqhq1025. It is not an independent human review and does not replace one.

[Astro-Han]

Reviewed head 770899d5819401cf3f008b5e3a1abb56ee2b76d6. The only change since the previously reviewed 769dcebf is a merge of upstream main (1e80e3b88, the current origin/main). Its one conflict, in apps/desktop/renderer-architecture.json, re-baselines AppShell's nonTriviaTokens (9576 -> 9347) and shifts line numbers. Apart from that file, the PR's diff against main is byte-identical to the earlier diff against c838e1fa. The merge with main is clean, git diff --check passes, and no packages/ or protocol files are touched.

I re-checked that /compact behaves the same as before the move:

• Command routing: composer-submit.ts (slashCommand.kind === 'compact', which reads activeIdRef and then calls ports.compactSession) is unchanged. AppShell now passes in the controller's stable compactSession instead of a function it rebuilt on every render.
• Bridge: createDesktopConversationServices spreads bridge.sessions, so services.sessions.compact is still window.maka.sessions.compact.
• Switching sessions during compaction: the new isCurrentSession reads workspace.activeIdRef. That is the same ref behind the activeIdRef (publishedSession) that AppShell used before, so a rejected request is still reported only while its Session is current.
• Error reporting: the workspace-unavailable toast and the generic compactErrorTitle/compactErrorFallback toast show the same copy with the same { sessionId } diagnostic target as showSessionWorkspaceUnavailableToast / showSessionError.
• Busy and in-flight guards: composer submission still owns them, and they are unchanged.
• Host outcome: ConversationLifecycle sets onContextCompactionOutcome after ...props, pointing at commands.finishContextCompaction. That is the same presentation the command uses, so the running notice is still dismissed. The presentation now lives as long as the controller instead of being rebuilt whenever toastApi changes, which does not lose anything.

Validation on Node 22.23.2: build:workspace-deps, build:test, typecheck (preload/main/renderer/storybook) and check:architecture pass. 26/26 focused tests pass (conversation-compaction, conversation-owner, app-shell-command-actions, session-reference-composer and related). The full dist/main suite passes 3091/3091. The earlier automated review (5370830715) had no findings, so there was nothing to re-verify.

Findings: no substantiated P0-P3 issues.

Not exercised: the Electron e2e/slash-command-compact.spec.ts journey, a live Host compaction, and Node 24.

Automated review notice: This comment was posted by an automated review agent. It is not an independent human review and does not replace one.

[Astro-Han]

Thanks @chihumyum — this was approved for merge, but it now conflicts with main after #5892 landed (both touch AppShell and the renderer architecture manifest). Could you merge or rebase onto current main? We'll re-check the new head and merge once CI is green.

[Astro-Han]

Reviewed e9aa420983bca25002d60ec71d13234fd5e1df1c. The only change since my previous review of 770899d5 is the merge of upstream main (0b25078b7), which brings in recent landings on the base branch rather than new work on this refactor.

No P0–P3 findings.

What I checked on the merge, since it touches two files this branch also edits:

• app-shell.tsx keeps both sides' work: the compaction wiring this refactor owns (compactSession, Conversation.ConversationLifecycle) is still present alongside the three Diagnostics.* usages that arrived with main's diagnostics extraction. The merge combined the two, it did not clobber either.
• renderer-architecture.json carries the merged re-baselining, and the head's test job is green on it.
• No file under packages/ui or packages/core is touched by this branch beyond what main itself changed, so the refactor's own surfaces are untouched by the merge.

My earlier verification still stands, and the merge does not disturb any of it: the /compact command routing, the bridge spread that keeps services.sessions.compact intact, the isCurrentSession check reading the same activeIdRef behind publishedSession, the identical error copy and diagnostic target, the composer-owned busy/in-flight guards, and onContextCompactionOutcome still pointing at the same presentation. Nothing in the merged files changes those paths.

Gate on this head: test is green.

What I could not judge

• The Electron e2e/slash-command-compact.spec.ts journey, a live Host compaction, and Node 24 — same gaps as the previous pass, unchanged by a merge-only delta.

I did not approve, request changes, or merge.

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Automated review notice: This comment was posted by an automated review agent operated by Astro-Han. It is not an independent human review and does not replace one.

[Astro-Han]

Thanks @chihumyum for the quick merge of main — the conflict resolution keeps both this refactor and the #5892 diagnostics extraction intact. Merging now.

[Astro-Han]

Approved at @Astro-Han's explicit request: the automated re-review of this head (a merge of main to resolve the conflict with #5892) found no P0–P3 issues, CI is green and the branch has no conflicts.