feat(tui): add inbox session workflow

[R44VC0RP]

Summary

• add an optional tabs.layout: \"inbox\" presentation with Active/Today/Yesterday/Earlier groups, recency ordering, assistant previews, unread state, and stable numbering
• add keyboard and pointer workflows for focusing the inbox, moving through visible rows, opening sessions, confirming tab completion, creating new tabs, and returning focus to the prompt
• keep top-strip behavior as the default and fall back to it on narrow terminals
• remove deferred session-mount scroll corrections that caused a visible tab-switch jump
• roll terminal execution timestamps through the full session ancestor chain so nested subagent activity preserves parent inbox recency after restart

Interaction

• left from an empty prompt focuses the inbox
• up / down / tab / shift+tab move through visible sessions
• enter opens the selected session
• press space twice to mark a tab done and close it
• option/alt+1-9 selects the matching visible inbox row; ctrl+x, then 1-9 remains available
• option/alt+t or ctrl+x, then n creates a new tab and focuses its prompt
• /tabs switches between inbox and top-strip layouts

Testing

• packages/tui: bun test (595 passed, 5 skipped)
• packages/tui: bun typecheck
• packages/core: bun test test/session-projector.test.ts (14 passed)
• packages/core: bun typecheck
• repository pre-push monorepo typecheck (33 packages)

[opencode-agent]

Requesting changes for four concrete regressions:

1. packages/tui/src/config/v1/keybind.ts:88 adds ctrl+t to session_new, while variant_cycle still owns the same default at line 142. Both commands are registered in the global app layer, so this shadows an existing default action. Keep ctrl+t on one command only or explicitly migrate the variant shortcut.

2. packages/tui/src/component/session-inbox.tsx:104-119 hides attention whenever a session is busy and renders the ordinary activity spinner instead. Sessions remain busy while blocked on permission/form input, so the inbox loses the signal that user action is required. Attention should override busy, matching the top-tab implementation.

3. packages/tui/src/component/session-inbox.tsx:184-190 and packages/tui/src/context/session-tabs.tsx:121-125 group and order rows from cached SessionInfo.time.updated. Live input/message/execution events update the local message/status stores but not that timestamp, so a background session can complete new work and fall back to an old position or remain under Yesterday/Earlier. Use a live activity timestamp or advance cached recency on relevant events.

4. packages/tui/src/app.tsx:1242-1253 consumes a 28-40 column rail, but packages/tui/src/routes/session/index.tsx:202-209 still computes the wide breakpoint, sidebar visibility, and content width from the full terminal width. At widths just over 120 this can auto-open the 42-column sidebar after the inbox has already consumed roughly a third of the viewport, and downstream rendering receives a width larger than its actual container. Base those calculations on the post-inbox viewport or account for the rail centrally.

Non-blocking style cleanup: session-inbox.tsx:208 adds an else if; the repository guide asks us to avoid else. Return after the top-scroll branch, then check the bottom branch.

Validation: packages/tui has 591 passing tests, 5 skipped, and bun typecheck passes locally. git diff --check also passes.

[opencode-agent]

Reviewed the follow-up at dbd9346: the ctrl+t collision is removed, attention now overrides busy presentation, inbox recency tracks live activity, and session layout calculations use the post-inbox viewport. The else branch was also removed. Local packages/tui validation: 593 passed, 5 skipped; bun typecheck passed; scoped oxlint reported no errors.

[opencode-agent]

One remaining correctness gap before merge: packages/tui/src/context/session-tabs.tsx:227 hydrates a root with data.session.sync(sessionID, { children: true }), but that API fetches only sessions whose parentID is the root. updated() can fold every loaded family member, yet after a restart grandchildren and deeper descendants are absent, so nested-subagent completion recency is still lost. This is a supported shape—the data context explicitly indexes arbitrarily deep families. Please either hydrate descendants recursively (and add a root -> child -> grandchild restart test) or roll terminal activity up to ancestors in the projector so loading the root is sufficient. Everything else in 7295315 looks good; all GitHub checks pass, and local TUI tests/typecheck plus the core projector test pass.

[opencode-agent]

Re-reviewed 094dac1. Terminal execution activity now rolls up through the full ancestor chain, guards against cycles, and only advances timestamps; the new root/child/grandchild projector test covers the restart gap. Local core projector suite passes (14/14). This resolves my remaining finding; code is ready once the current CI run is green.