fix(copilot): load workflow chat history through the windowed chat routes

[waleedlatif1]

Summary

• Workflow Copilot panel chats are stored as copilot chats, but the chat detail route only served mothership chats. Every panel history load got a 404 and fell back to the legacy /api/mothership/chat?chatId= read, whose response has no mode — which the history parser requires — so the panel showed "Failed to load chat history" on every load and refetch, after reading the whole transcript
• The chat detail route now serves both chat types; its authorization (authorizeCopilotChatRow) already checks workflow read for workflow chats
• Older pages and stream status serve copilot chats too, behind the same rule as the detail read: the workflow must still be readable, and a workspace Plan chat needs Plan mode on (requireOwnedChatReadable, sharing authorizeChatWorkflowRead / isChatModeAvailable with the detail read). Other chat use cases are unchanged for every chat that carries a workspace
• A workflow chat row from before chats carried a workspace (nullable workspace_id, never backfilled) is scoped through its workflow while its owner may read that workflow, so these chats load their older pages and stream status instead of being refused
• Removed the client 404 fallback and the now-unused legacy GET (app/api/copilot/chat/queries.ts, getAccessibleCopilotChat, its column set and query schemas); the list branch of that GET had no callers either. Shrunk the explicit-any, source-conventions and unused-exports baselines accordingly
• Rollout: a new client against an old server gets a plain 404 until the deploy finishes; the fallback it loses was already failing to parse

Type of Change

• Bug fix

Testing

• Integration: the mothership detail route on a workflow copilot chat returns 200 with its mode and the same snapshot handling (replay-budget.integration.ts; 404 on the current code); older pages and stream status serve a workflow copilot chat including a legacy row without a workspace, and refuse one whose workflow is archived (transcript-pages.integration.ts, read-stream-status.integration.ts; the served cases fail on the current code)
• Ran locally: focused unit tests for the chat lifecycle, detail route, chat history hook and chat application use cases (10 files, 129 tests), apps/sim type-check, biome, check:explicit-any, check:unused-exports, check:test-patterns, check:comment-hygiene, check:boundaries; type-check, full audits and integration suites run in CI

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated
docs	Skipped		Oct 16, 2026 5:28am UTC

[cubic-dev-ai]

All reported issues were addressed across 18 files

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[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge, with no new actionable issues found.

Summary

Workflow Copilot history now uses the windowed chat routes instead of the legacy fallback.

• Workflow Copilot history loads through the windowed chat route.
• Older transcript pages and stream status now include readable workflow chats.

_{Reviews (2) · Last reviewed commit: "test(copilot): name each workflow chat f..." · Reviewed by Greptile}

[waleedlatif1]

@greptile