vscode: Quick Pick command for searching the backlog

[amrmelsayed]

Problem

The Backlog tree has no in-sidebar search. Users have:

• area/* grouping (vscode: group backlog by area (area/* label namespace, predictable across views) #811) — narrows by area, requires the user already knows the area
• Mine-only toggle (vscode: backlog view — toggle between 'mine only' (default) and 'all' #809, vscode: Backlog tree title-count should reflect the active view mode, not the total spawnable set #911) — narrows to assigned items
• VSCode's generic type-to-search — prefix-match against the visible label only

For finding a specific issue by recall ("the one about webview... something") or by topic ("anything mentioning telemetry"), none of the above help. The sidebar-embedded-input path was closed as not-doable in pir-891 (VSCode's TreeView API has no <input> primitive). The full-webview Backlog path is tracked at #906 but is heavier-weight and orthogonal to a fast find-and-open affordance.

Proposal

Add a Quick Pick command — VSCode's first-class vscode.window.showQuickPick primitive, the same overlay UI that powers Cmd+P (Go to File), Cmd+Shift+P (Command Palette), Cmd+T (Go to Symbol), etc. Built-in fuzzy match, native styling, familiar keyboard nav. No webview, no TreeView limits.

Concretely:

• Register command codev.searchBacklog (palette title: Codev: Search Backlog...).
• Invoking it snapshots the current backlog from the shared overviewCache (same source BacklogProvider reads from — no new data path).
• Maps each backlog item to a vscode.QuickPickItem:
  • label: #909 <issue title>
  • description: <area/label> · <#days> ago (if assignee present, append · @<assignee>)
  • detail: optional — possibly the issue body's first sentence, truncated to ~120 chars (decision left to implementation if it bloats the picker)
• Calls vscode.window.showQuickPick(items, { placeHolder: 'Search backlog by id, title, area, assignee...', matchOnDescription: true, matchOnDetail: true }).
• On selection: invoke codev.viewBacklogIssue with the chosen item's issue id (the same default action the sidebar row uses when single-clicked — views/backlog.ts:128-129). User gets the issue opened the same way they would via the sidebar.
• No default keybinding — leave bindings to user preference (avoids conflicts with VSCode and other extensions). Command is discoverable via the palette.

Design decisions inside the AIR

A few small calls the implementer should pick during the AIR, with the recommended default noted:

1. Filter scope vs the mine-only toggle: search always over the full backlog, not just mine-only. Searching is a discovery affordance; restricting it to the user's assigned set would surprise a user looking for an issue they didn't author. The mine-only toggle remains a tree affordance only.
2. Snapshot vs live: snapshot at invoke time. Quick Pick is a one-shot; live-updating items while the user is typing is jittery and not what Cmd+P does either.
3. Sort order: same as the tree (assigned-to-current-user first, then by area, then by issue number descending). Within fuzzy-match results VSCode handles ranking, but the input order matters when the user just opens the picker without typing.
4. Closed issues: out — only open issues, matching the sidebar.
5. alwaysShow: false: default — VSCode hides non-matches once the user types. (true would keep all rows visible which defeats the search.)

Acceptance

• Codev: Search Backlog... appears in the command palette.
• Invoking it opens a Quick Pick populated with every open backlog issue.
• Typing fuzzy-filters by id, title, area, or assignee.
• Selecting a row opens the same view that single-clicking the sidebar row would (the codev.viewBacklogIssue flow).
• Esc / clicking outside dismisses with no side effect.
• Works whether or not the Backlog sidebar view is visible/expanded.

Out of scope

• Per-row buttons in the Quick Pick (open in browser, copy issue number, etc.). Could be added later; not required for v1.
• A default keybinding. Users add their own.
• A persistent "Backlog with search input always visible" view — that's vscode: full webview Backlog for unified search input (Path B — replaces #891 stealth-merge) #906's path, intentionally orthogonal.
• Searching closed issues, PRs, or any other surface than the open backlog.
• Live updates while the picker is open.

Why AIR (not BUGFIX, not PIR, not SPIR)

• BUGFIX is for bugs; this is a feature.
• PIR's pre-PR running-app gate adds latency that isn't load-bearing here — the affordance is a discrete picker, easy to verify in the PR diff plus a manual five-second exercise.
• SPIR's spec/plan ceremony is overkill for a ~60-100 LOC command registration with no architectural decisions.
• AIR fits: small, well-scoped, no design ambiguity left after this issue body.