docs(handoff): dl-router Discord media — three PRs merged and shipped, and the consumer is MEASURED not to be running them

[ZacxDev]

New effort, new doc — the two existing dl-router handoffs are closed retrospectives of the July/August build-out with dated slugs, not this work.

Discord is 59% of dl-router's live traffic (20 of 34 routed downloads) and the routing half has been Discord-specific since the first evening — but the save side was wrong for it in three ways. All three merged and shipped:

PR	squash	what
#1110	911af220	save the file that was POSTED, not the proxy thumbnail; a stable ledger key for a signed CDN URL; Discord attachments bypass the yt-dlp branch
#1113	4fdead27	the sibling discord-embed-ext doc — crop VERIFIED LIVE, plus three corrections
#1149	67f674f6	media may be an ORDERED LIST of accessors, so one rule covers an anchor-linked image AND a direct video

The part that matters most

🔴 Deployed ≠ running. After the operator reported reloading, I measured Brave's own record:

dl-router bytes in the repo tree	0.3.2, written 08-31 02:41
last reloaded (Brave's Preferences)	08-30 21:39 — five hours before those bytes existed
Brave main process	up since 08-28 — no restart at all

Brave is still running 0.3.1. That is what the manifest bump exists to detect, and it is rank 1 in the doc with forcing: user.

Open investigation carried forward

Whether preferOriginalUrl is a no-op in production. The defect it fixes is proven (pre-change code demonstrably downloads …?format=webp&width=550), but all 20 live Discord rows are origin-host, so the proxy branch has no live instance behind it — and the extension has no logging facility, so the question has no data-driven answer. The doc carries the DOM probe that settles it, and both eliminations are tagged via: measurement with the untested part named explicitly.

Also recorded

The two-writers-one-reader ledger seam and why buildMatchPayload is deliberately not folded in (pinned by three pre-existing tests); why store.source_url_key keeps the query on purpose and Discord is the exception; the hand-copied MAX_MEDIA_ACCESSORS that left both suites green when only one side moved; that a menu test asserting only downloads.length === 0 is vacuous (hit twice in one PR); and the asymmetric deploy order — switch first, rule second, or a list rule against the old sidecar takes every routing endpoint to 503.

Docs-only: one file.

🤖 Generated with Claude Code