Local usage statistics dashboard (split re-landing of #1225) #1744

Summary

Re-land the local usage statistics dashboard as a series of small, sequential PRs, replacing the closed #1225 (52 commits / +41k lines — "too large to safely review"). The feature was already fully reviewed and hardened: all 59 CodeRabbit findings triaged (23 majors + 4 minors applied on top of the already-fixed critical/data-integrity cluster), and the branch is semantically current with main (typecheck clean, 1,142 targeted tests green in a test merge).

Why it must be split

The CI mutation gate caps changed executable lines at 500 per package (extension / webview); the feature totals ~6,781 (extension) + ~2,071 (webview). Sequential stages, each independently green:

1. S1 — shared types & message contracts (packages/types) — this is the tracking issue's first PR
2. E1 — cost recalculation & capture primitives (~299 ext lines)
3. E2 — usage aggregation & query-range (~382)
4. E3–E7 — stats database core, migrations, append/read (~378–487 each)
5. E8–E9 — event store, migration runner, task catalog (~437, ~416)
6. E10–E13 — DB queries, rollup writers, projections (~339–492)
7. E14–E16 — stream coordinator, service façade, task capture (~435, ~360, ~368)
8. E17–E18 — message handlers & activation (~428, ~489)
9. W1–W5 — webview UI: leaf components, task list, stream state, view logic, tab (~331–445 wv lines each)

Each stage PR references this issue; the stages merge strictly in order, and each subsequent PR is opened once its predecessor lands on main. The gate-loosening changes that were (rightly) rejected on #1225 are not carried over.

Source

Feature tree: myk1yt/feat/dashboard (archived) → clean integration base myk1yt/feat/dashboard-reboot (upstream/main + feature + all review fixes).