[AIR #1108] vscode: open architect terminal on Agents-view group-header click

[amrmelsayed]

Closes #1108.

Summary

In the Agents view's architect-axis grouping mode, clicking an architect
group header (e.g. MAIN, VSCODE) now opens that architect's terminal,
matching the builder-row affordance. The chevron continues to toggle
expand/collapse independently (VS Code routes the row command and the chevron
gesture separately — the same pattern builder rows already use).

This removes the asymmetry where the architect-axis grouping made the architect
first-class, but its header was a less interactive surface than the builder
rows nested under it.

Changes

• packages/vscode/src/views/builders.ts — rootChildren() now sets
  item.command = { command: 'codev.openArchitectTerminal', title: 'Open Architect Terminal', arguments: [g.key] }
  on each group header only when the active grouping axis is architect
  (grouping.id === 'architect'). g.key is the architect name.
• packages/vscode/src/__tests__/builders-architect-header-command.test.ts —
  new unit tests.

Key decisions

• Scoped to architect headers only. Stage (SPECIFY, …) and area
  (TOWER, …) headers name no launchable entity, so they stay command-less
  containers. The gate is grouping.id === 'architect', checked once per render.
• main fold preserved. A null spawnedByArchitect folds into the main
  bucket in architectGrouping(); the main header therefore opens the main
  architect terminal (arguments: ['main']), consistent with the fold.
• No command-handler change. codev.openArchitectTerminal already accepts
  the optional architect-name argument (Multi-architect feature is underbaked — gaps in lifecycle, persistence, and UX #786 Phase 6) and already handles a
  stale / not-found owner gracefully — it shows a No '<name>' architect found
  warning (the same path the Workspace > Architects right-click takes). So the
  stale-owner edge from the issue's scope notes needs no extra work here.
• No package.json / menu changes. This is a row command (left-click),
  not a view/item/context menu entry, so no contribution-point wiring is
  needed.

Test plan

• pnpm test:unit (vscode package): 43 files / 516 tests pass, including the
  4 new tests:
  • architect headers carry codev.openArchitectTerminal with the architect
    name as the argument;
  • a null spawnedByArchitect yields a main header that opens the main
    terminal;
  • stage headers carry no command;
  • area headers carry no command.
• porch check: ✓ build ✓ tests.

Out of scope (per issue)

• Right-click context menu on architect headers (e.g. "Open Worktree Folder").
• Launch affordance from stage / area modes (Workspace > Architects remains the
  surface there).

[amrmelsayed]

Architect Review

Low-risk AIR PR. Verified the implementation independently against PR head.

Implementation

packages/vscode/src/views/builders.ts:295-318 — clean. The isArchitectAxis gate is computed once outside the groups.map(g => ...) loop, and the command is set on each group header only when the architect axis is active. Stage and area headers stay command-less. The inline comment names every scope note from #1108: chevron routes independently for expand/collapse, g.key is the architect name (null owners folded into main per architectGrouping), and stale-owner handling rides on codev.openArchitectTerminal's existing graceful-warn behaviour.

const isArchitectAxis = grouping.id === 'architect';
return groups.map(g => {
  const groupItem = new BuilderGroupTreeItem(...);
  if (isArchitectAxis) {
    groupItem.command = {
      command: 'codev.openArchitectTerminal',
      title: 'Open Architect Terminal',
      arguments: [g.key],
    };
  }
  ...
});

Test coverage

builders-architect-header-command.test.ts pins all four scope notes:

• Architect headers carry the command — independently verified for main and a named sibling (vscode).
• main fold for null spawnedByArchitect — a builder with null owner produces a main group header that opens main's terminal.
• Stage headers have no command — pure grouping containers.
• Area headers have no command — same, with two-area fixture to bypass the lone-Uncategorized flatten so real area headers actually render.

Mocks vscode per the established __tests__ pattern (matches builders-autoreveal.test.ts).

Risk and scope

17 net lines in builders.ts (7 of code + 6 of comment, plus the isArchitectAxis const above the loop), 169 lines of test. Exactly the "5-line wiring + small unit test" scope #1108 anticipated. No new dependencies, no API surface change, no migration. Build / unit / e2e all green per the builder's report.

Recommendation

APPROVE. Ready for the pr gate.

---

Architect review