werkator/docs/plan/19-watcher-health-in-ui.md

Step 19: Show a stalled watcher in the web UI

Prerequisites: none — the data already exists, only nothing renders it. Read README.md first.

Why

On 2026-08-30 the Gitea token in the machine config on vm4006 was replaced by a placeholder string. For 57 minutes GitTally failed git fetch --prune origin every ten seconds and wrote 297 warnings to the journal. The branches view showed a calm, ordinary list the whole time: every branch with its last build, nothing amiss. The failure was noticed only because an expected build did not start, and it took reading the journal to see why.

A watcher that cannot reach origin means every branch row on the page is stale — the one thing the page exists to tell. Silence is the wrong answer, and the journal is not the user interface.

What Already Works

Watcher.poll records the failure: state = state.copy(lastPollAt = …, lastFetchError = e.message ?: …), cleared again after a clean cycle. WatcherApiController serves it at /api/watcher as WatcherState, which distinguishes three failure modes:

• lastFetchError — origin unreachable (credentials, network, gone remote);
• lastPollError — the cycle crashed after a successful fetch;
• running: false — the poll loop is not scheduled at all.

All three mean the same thing to a reader: what you see is not current. The endpoint needs no change.

Code

• static/gittally.js: fetch /api/watcher from the same polling cycle that refreshes the view, and show a banner while any of the three conditions holds. Keep the existing discipline — a timeout on the fetch, and a failure of this request must never break the view's own refresh.
• templates/fragments.html: add a watcher-banner fragment to the nav(view) row so every view inherits it; hidden unless the script fills it.
• Wording says what is stale and since when, not just that something failed: the branch list is not updating, since lastPollAt, because <error>. Timestamps go through the shared formatting — UiFormats and gittally.js must produce identical formats (invariant in AGENTS.md).
• Do not overload live-indicator: it reports whether the browser reaches the server. This banner reports whether the server reaches origin. Two independent failures, two independent signals.

While in there, fix the logging volume: one outage produced 297 identical warnings. Log the fetch failure when its message changes, not on every cycle, and log once more when the fetch succeeds again. This is the same class as the atTimes warning that repeats every poll for an invalid slot — fix both or neither, but do not leave the new one behind.

Tests

• server/WatcherApiControllerTest.kt — assert that a state carrying lastFetchError reaches the JSON, so the field the UI depends on is covered.
• watcher/WatcherTest.kt — a failing fetchOrigin sets lastFetchError and a following clean cycle clears it; a repeated identical failure logs once.
• The JavaScript has no test harness; the banner is verified manually below.

Verification

• Break it deliberately in a scratch repo install: set git.token to a wrong value, and watch the banner appear within one poll interval and disappear again after fixing it.
• Stop the watcher (running: false) and confirm the banner says so in its own words rather than reporting a fetch error.
• On a narrow viewport the banner must not push the table off screen.