Rewinding a desktop session can race with a still-exiting CLI process,
leaving late transcript entries after the trim point. Desktop placeholder
sessions also need to preserve canonical launch metadata so a zero-message
rewind can restart from the real workspace instead of reconstructing it from
a lossy sanitized project directory name.
Constraint: Rewind must work after trimming back to an empty transcript.
Constraint: Session project directory names are sanitized and not reversible.
Rejected: Add retries around CLI startup | would leave corrupted transcript state in place.
Rejected: Delete desktop placeholder files before first CLI launch | drops the only reliable workDir metadata.
Confidence: high
Scope-risk: moderate
Directive: Do not change rewind process stopping without rechecking late CLI output and transcript metadata preservation.
Tested: Real DeepSeek deepseek-v4-pro rewind smoke, bun test src/server/__tests__/sessions.test.ts --timeout 30000, bun test src/server/__tests__/conversations.test.ts --timeout 30000, bun run check:server, bun run check:native, bun run quality:pr, git diff --check
Not-tested: Native Windows desktop binary smoke for the original reporter environment.
The chat timeline lost per-turn changed file cards when the visible user message ids did not match persisted transcript ids, and sessions without SDK file-history snapshots had no fallback source for turn changes. Match live cards by stable user-message index when needed and derive checkpoint previews from transcript tool calls when snapshots are absent.
Constraint: Right-side workspace changes already derive from transcript tool calls, so chat checkpoint data must remain consistent with that source.
Rejected: Force a history reload after every turn | would hide the id mismatch but add churn and still not cover transcript-only sessions.
Confidence: high
Scope-risk: moderate
Directive: Keep snapshot checkpoints as the preferred source, and use transcript extraction only as the compatibility fallback.
Tested: bun test src/server/__tests__/sessions.test.ts
Tested: bun test src/server/__tests__/workspace-service.test.ts
Tested: cd desktop && bun run test src/components/chat/MessageList.test.tsx
Tested: cd desktop && bun run lint
Tested: cd desktop && bun run test
Tested: git diff --check
Not-tested: Browser E2E against a live model session.
The desktop workspace panel and chat transcript were mixing project-level file state with per-turn session history, which made rewind, file attachment, and changed-file previews brittle across multi-turn and historical sessions. This keeps turn checkpoints durable in the transcript, makes workspace refreshes happen at the right lifecycle points, and hardens long file previews without blocking the UI.
Constraint: Right-side workspace changes are project working-tree state, while chat turn cards are session checkpoint state.
Rejected: Treat every changed-file panel entry as session-local | new sessions must still reveal existing dirty project files.
Confidence: high
Scope-risk: moderate
Directive: Do not couple global workspace status to session checkpoint cards without preserving both product meanings.
Tested: cd desktop && bun run test src/components/workspace/WorkspacePanel.test.tsx
Tested: cd desktop && bun run lint
Tested: git diff --check
Tested: cd desktop && bun run test
Not-tested: Packaged Tauri runtime smoke test
Workspace inspection now shares the same diff renderer between chat change cards and panel previews, supports scoped preview-tab closing, confirms checkpoint undo, resolves rewind checkpoints from the prompt cwd, and removes light-only workspace chrome so dark theme remains coherent.
Constraint: Workspace review must keep working for existing transcript sessions and non-git session-derived changes.
Rejected: Keep a separate chat diff preview | it drifted from panel rendering and dark theme behavior.
Confidence: high
Scope-risk: moderate
Directive: Keep chat and workspace diff rendering shared so theme and truncation behavior do not diverge again.
Tested: cd desktop && bun run test -- src/components/workspace/WorkspacePanel.test.tsx src/components/chat/MessageList.test.tsx src/stores/workspacePanelStore.test.ts
Tested: cd desktop && bun run lint
Tested: cd desktop && bun run build
Tested: bun test src/server/__tests__/sessions.test.ts
Tested: Browser dark workspace preview at http://127.0.0.1:59468/ with src/App.jsx diff
Not-tested: macOS packaged app build
Workspace inspection was visible only as a side panel, while file restore still lived behind the older per-message rewind affordance. This adds a chat-flow change card for the completed turn, keeps undo routed through checkpoint rewind, and tightens the workspace split layout so narrow and fullscreen windows keep both chat and file preview usable.
Constraint: Current session file changes must work for non-Git directories when transcript tool edits are available
Constraint: Workspace preview must remain right-docked without horizontal overflow across narrow and wide desktop viewports
Rejected: Keep only hover rewind | users could not clearly see what the current turn changed before undoing it
Rejected: Use Git as the only changed-file source | many desktop sessions run in temporary or non-Git directories
Confidence: high
Scope-risk: moderate
Directive: Keep checkpoint rewind as the source of truth for undo semantics; workspace diffs are a preview surface, not the restore authority
Tested: bun test src/server/__tests__/sessions.test.ts src/server/__tests__/workspace-service.test.ts
Tested: cd desktop && bun run test -- src/components/chat/MessageList.test.tsx src/components/workspace/WorkspacePanel.test.tsx src/stores/workspacePanelStore.test.ts src/pages/ActiveSession.test.tsx
Tested: cd desktop && bun run lint
Tested: cd desktop && bun run build
Tested: bun /tmp/cc-haha-layout-e2e/run-layout-e2e.mjs
Not-tested: Native Tauri packaged app window chrome behavior
Desktop rewind previously used the visible user-message index as the primary selector. That can drift from the persisted active chain when hidden or non-rendered user messages exist, so the API now prefers a stable user message id and checks the selected prompt text before mutating transcript or files.
Constraint: Desktop UI can hide transcript entries that still exist in the persisted session chain
Rejected: Keep index-only rewind | can target an earlier user message after UI/server chain drift
Confidence: high
Scope-risk: moderate
Directive: Do not remove targetUserMessageId or expectedContent guards without reproducing shifted visible-index sessions
Tested: bun test src/server/__tests__/sessions.test.ts --timeout 20000
Tested: cd desktop && bun run test MessageList.test.tsx chatStore.test.ts -- --run
Tested: desktop/scripts/e2e-rewind-agent-browser.sh
Tested: desktop/scripts/e2e-rewind-complex-agent-browser.sh
Not-tested: Full desktop Vitest suite still has unrelated locale-sensitive failures
The desktop client already had a conversation-level rewind UI concept on the
CLI side, but the web/desktop surface lacked the protocol, session trimming,
and file checkpoint restore path needed to make rewind trustworthy. This change
adds a desktop-specific rewind API, wires the message-level UI affordance and
confirmation modal, enables SDK file checkpointing for desktop sessions, and
covers the restore path with service tests plus a real agent-browser workflow.
Constraint: Desktop sessions run the CLI in SDK/print mode, so file checkpointing had to be enabled explicitly for that path
Constraint: main branch is checked out in a separate worktree, so merge-back must happen from the primary worktree after commit
Rejected: UI-only rewind that only trims local state | would leave persisted transcript and disk state inconsistent after refresh
Rejected: Reuse getLastSessionLog as the sole snapshot source | active rewind must read file-history metadata directly from the session file
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Keep desktop rewind keyed to persisted user-message order unless the UI model starts carrying stable transcript UUIDs end-to-end
Tested: bun test src/server/__tests__/conversation-service.test.ts src/server/__tests__/sessions.test.ts; desktop MessageList vitest; desktop tsc no-emit; live agent-browser E2E on isolated ports with file edit then rewind
Not-tested: Browser E2E matrix for multi-file and second-edit scenarios is still covered at service-test level rather than full UI level
