feat(youtube): process-wide caption-fetch rate gate (ADR-014 item 2)

ADR-014 item 2 — a single per-egress-IP rate gate shared by every caption
fetch — was specced but only per-video backoff (rate_limited_at) shipped.
Build the real gate now: it is load-bearing once ADR-018 puts auto-summarize
on an in-process schedule across multiple users (all fetches leave one pod's
egress IP, concurrently with live "Summarize" clicks — without a shared gate
that self-inflicts 429s every cycle).

globalFetchGate (golang.org/x/time/rate, default 2s/req burst 1) is consulted
in httpDo before every live outbound fetch — player, watch-page, timedtext —
so the scheduler runners and the web click-path serialise through one limiter
regardless of how many users/goroutines are upstream. The test seam
(a.transport != nil) skips the gate so fakes are not throttled.

TAPIR_FETCH_RATE (Go duration, default 2s, 0 = unlimited) wires SetFetchRate in
cmdRun; the existing per-video backoff stays as the complementary 429 handler.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

This commit is contained in:

mathias

2026-06-05 23:36:17 +02:00

co-authored by

Claude Opus 4.8

parent 88294d38bc

commit f5021a8436

8 changed files with 176 additions and 1 deletions

									
										go.mod
									
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				@@ -12,6 +12,7 @@ require (

					github.com/stretchr/testify v1.11.1

					golang.org/x/crypto v0.45.0

					golang.org/x/oauth2 v0.36.0

					golang.org/x/time v0.15.0

				)

				require (