refactor(workspace): split workspace.tsx into panels and hooks

[liam-russell]

Type

• refactor — internal change, no behavior change

Summary

• No user-visible change. Internal-only: split the 1,728-line workspace.tsx into focused panel components (WorkspaceHeader, GraphTabPanel, TerminalTabPanel, WorkspaceDialogs) and data-fetching/subscription hooks under app/src/renderer/hooks/ (terminal session management, worktree selection, commit diff state, file watchers, UI persistence, etc.), leaving workspace.tsx as a ~600-line composition root.
• Also fixed the two pre-existing no-unstable-nested-components lint warnings in WorktreeSidebar.tsx by hoisting its inline context-menu builders (used by the row right-click menu and the "…" quick-actions menu) to module-level functions that take their dependencies as parameters.

Why

workspace.tsx was ~3x the next-largest renderer file and the highest-friction file in the repo — most feature work lands there. Splitting it into panels/hooks unblocks other renderer work (#117).

Screenshots / recordings

N/A — pure refactor, no visual or behavioral change.

Breaking changes

None.

Test plan

• pnpm lint, pnpm typecheck, pnpm test all pass.
• pnpm --filter app build && pnpm test:e2e — full E2E suite passes (14 spec files, all green), including daily-workflow, worktree-workflow, commit-workflow, file-editor-workflow, agent-workflow, and sidebar-collapse — the specs most likely to catch a regression from this move.
• Manually booted pnpm dev and confirmed the app launches cleanly with no renderer console errors.
• No exported function/type names changed, and no external imports of workspace.tsx internals existed, so no other files needed updates beyond the two touched here.

Closes #117

[Copilot]

Pull request overview

Refactors the renderer workspace route by decomposing the previously very large workspace.tsx into focused panel components and reusable hooks, aiming to reduce coupling and make workspace feature development easier while preserving existing behavior.

Changes:

• Extracted top-level UI sections into dedicated panels/components (header, graph tab, terminal tab, dialogs).
• Moved stateful workspace behaviors (worktree selection, terminals, watchers, UI persistence, recent workspaces, etc.) into hooks under app/src/renderer/hooks/.
• Refactored WorktreeSidebar context/quick-action menus to module-level builders to address unstable nested component lint warnings.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
app/src/renderer/routes/workspace.tsx	Turns workspace.tsx into a composition root by wiring extracted panels + hooks.
app/src/renderer/workspace/WorktreeSidebar.tsx	Hoists menu-building logic to module scope and applies formatting/refactor cleanup.
app/src/renderer/workspace/WorkspaceHeader.tsx	New header component encapsulating titlebar chrome + workspace switcher.
app/src/renderer/workspace/GraphTabPanel.tsx	New graph tab wrapper that owns graph + diff panel wiring.
app/src/renderer/workspace/TerminalTabPanel.tsx	New terminal tab wrapper for session tabs, shell picker, and panes.
app/src/renderer/workspace/WorkspaceDialogs.tsx	New component bundling workspace modal dialogs into one place.
app/src/renderer/hooks/useWorktreeSelection.ts	New hook encapsulating initial selection + switch/delete/create-hook flows.
app/src/renderer/hooks/useTerminalManager.tsx	New hook encapsulating terminal lifecycle, buffers, and context menu actions.
app/src/renderer/hooks/useWorkspaceFileWatchers.ts	New hook consolidating watchers/subscriptions and workspace-switch cleanup.
app/src/renderer/hooks/useWorkspaceUiPersistence.ts	New hook for sessionStorage mirroring and sidebar shortcut wiring.
app/src/renderer/hooks/useRemoteOps.ts	New hook for fetch/pull/push actions and in-flight state mirroring.
app/src/renderer/hooks/useRecentWorkspaces.ts	New hook for recent workspace list loading + navigation switching.
app/src/renderer/hooks/useCommitDiffState.ts	New hook for commit/range diff selection state used by the graph tab.
app/src/renderer/hooks/useScaffoldKickoff.ts	New hook for “new from idea” scaffold kickoff behavior.
app/src/renderer/hooks/useAgentConfig.ts	New hook for loading the AI agent configuration.
app/src/renderer/hooks/useAvailableShells.ts	New hook for loading shells used by the terminal shell picker.
app/src/renderer/hooks/useAutoUpdateListeners.ts	New hook wiring updater IPC events into the update store.
app/src/renderer/hooks/useEditorTabsForWorktree.ts	New hook deriving editor tabs scoped to the active worktree.
app/src/renderer/hooks/useFileEditorActions.ts	New hook for open/save/reload editor tab operations.