Baseline bars were positioned at their absolute timeline offset, which
included the baseline run's own wait time — making duration comparisons
hard since the bars were visually offset. Now each baseline bar starts
at the same left position as its corresponding current job, so the two
bars directly overlap for at-a-glance duration comparison.
Also removed the now-unused bl_t0 / bl_max / bl_jobs_timed variables
that tracked the baseline timeline position.
Add wait time computation: for each job, wait_s = started_at - max(completed_at
of all jobs that finished before it started). This is a timestamp heuristic
(no workflow YAML dependency parse needed) that's accurate for pipeline-shaped
CI where the critical path is linear at each stage.
Shows up in:
- Job table: new Wait + Δ Wait columns
- Gantt chart: hatched bar segment before the run bar
- Step details: '(wait Xs)' annotation in the summary line
- Markdown summary: Total wait row with delta vs baseline
- Stats: total_wait / bl_total_wait in compute_stats
Also completes the skipped-jobs UI:
- Skipped stat card in stats cards
- Skipped row in markdown summary table
Backward compatible: old cached baselines without wait_s annotate on load.
Skipped jobs (conclusion == 'skipped') have null/zero-duration timestamps
that polluted every downstream computation: they counted as 'unchanged'
(0 vs 0) in faster/slower tallies, showed meaningless '0.0s (0%)' deltas
in the job table, rendered phantom gantt bars, and inflated wall/compute
totals.
Add is_skipped() helper and apply it consistently:
- compute_stats: exclude from wall/compute + faster/slower/unchanged;
add 'skipped' and 'bl_skipped' counts
- _gantt_bars: filter from current bars, baseline bars, and axis calc
- _job_table: show 'skipped' label instead of durations/deltas
- _step_details: skip entirely (no meaningful step data)
- _regressions: exclude from both current and baseline sides
The 'CI timing report' job is pure observability — it collects per-job/step
durations from the GitHub API after the run and publishes an HTML gantt
report + PR-vs-main timing diff. It gates nothing (all-checks-pass does not
include it), yet it could redden a PR: the script makes dozens of paginated
API calls with the shared repo GITHUB_TOKEN and had zero retry handling, so
a single 403 (rate-limit burst when several PRs run CI concurrently) failed
the job. Observed twice in a row on PR #59805.
- api_get(): retry 403/429/5xx and connection errors with exponential
backoff, honoring Retry-After / X-RateLimit-Reset (max 5 attempts, 120s
cap). Non-transient statuses (404 etc.) still fail fast.
- main(): exhausted retries raise TimingsUnavailable, caught to emit a
degraded summary line + placeholder HTML artifact and exit 0 — a metrics
collector must never fail the PR's checks. No timings JSON is written on
the degraded path so an empty baseline can never be cached.
- ci.yml: baseline-save steps on main skip gracefully when no JSON exists.
Verified with a mocked urlopen harness: retry-then-success (3 attempts),
exhausted-retries -> TimingsUnavailable, 404 fails fast without retry,
degraded main() exits 0 with summary + placeholder and no JSON, and the
--from-json happy path is unchanged.
