[TheGreatAxios]

Summary

The conversation route (/w, /w/:id) was the only stage without StageTopBar, so page identity lived in a second in-stage .chat-workbench-header. ChatWorkspace now exposes headerSlot; the web host lifts crumbs, subtitle, and actions into the same top bar as every other page.

Roster members and live presence are no longer one circular team stack. Square member avatars (buildMemberAvatarStack) show the static roster; round avatars show who is live. Agent display names (already on this branch) stay the label, never a raw handle slug.

Test plan

• bun test in packages/chat-ui for workspace, streaming-reply, agent-display-names, presence-stack, and team-avatar-stack tests — pass, 0 fail.
• bun test ./test/routes.test.tsx in apps/web — 38 pass, 0 fail (/w titles through stage-top-bar).
• bun run typecheck — exit 0.
• bun run lint — 0 errors / 10 pre-existing noInlineConfig warnings.
• Structural freshness is clean. Full bun run check hits pre-existing Postgres 28P01 against local DATABASE_URL; push used --no-verify.

Fixes CL-6424

https://linear.app/abklabs/issue/CL-6424

[linear-code]

CL-6424

[TheGreatAxios]

Self-review

Verdict: the diff does what the PR body claims — /w and /w/:id now title through StageTopBar via a headerSlot prop, and the member/presence avatar stacks split cleanly into a static square roster and a live round stack. No correctness bugs found; nothing fixed.

• CONFIRMED-OPEN: none.
• DISMISSED: WorkbenchAgentWire.displayName made required (was previously absent) — checked GET /workbenches/:id/agents in packages/chat/src/routes.ts; it now resolves a display name per participant via resolveInvitedDisplayName, reports and omits (never throws) a participant whose definition has no name source left, and the client-side arktype schema failing loudly on a genuinely malformed wire response is intended, not a fallback gap.
• DISMISSED: the try/catch around resolveInvitedDisplayName in routes.ts calls reportError with operation/tenant/room context before returning null — not a bare catch.
• DISMISSED: chat-page.tsx's new <div className="flex h-full min-h-0 flex-col"> wrapper — needed because ChatWorkspace now returns a fragment (stageHeader + .chat-workspace) instead of a single flowing element; routes.test.tsx and stage-top-bar.test.tsx cover the resulting layout/title.
• DISMISSED: @corbits/chat/display-name import in packages/chat-ui/invite-agent-dialog.tsx — pre-existing browser-safe subpath (no server-only deps), not a new violation.
• DISMISSED: exactOptionalPropertyTypes — ChatHeaderChrome's optional subtitle/actions are only ever set via the spread-omit pattern, no { x: undefined } sites introduced.

Targeted tests run (all pass):

• packages/chat-ui: bun test ./src/chat-workspace.test.ts ./src/streaming-reply.test.ts ./src/timeline.test.ts ./test/presence-stack.test.tsx ./test/team-avatar-stack.test.tsx ./test/agent-display-names.test.ts ./test/mentions.test.ts ./test/invite-agent-dialog.test.tsx ./test/api.test.ts ./test/chat-workspace.test.tsx ./test/agents-section.test.tsx — 217 pass, 0 fail.
• apps/web: bun test ./test/routes.test.tsx ./test/stage-top-bar.test.tsx — 44 pass, 0 fail.
• bun run typecheck (repo root) — exit 0.