quest: dropped sources, video keyframe flag, interop flakes

quest/m1/README.md

@@ -22,8 +22,10 @@ transport, benchmark tooling); worktrees isolate commits, not semantics.
 - [Announce compression](/quest/m1/announce-compression.md) - a lite-07 announce reuses the path head and hop-chain tail of a live announcement on its stream instead of resending them
 - [lite-07 count settle](/quest/m1/lite-count-settle.md) - moq-lite-07 subscribers stop waiting for a subscription's tail once SUBSCRIBE_END's stream count is reached
 - [Session death error](/quest/m1/session-death-error.md) - a dying session ends its tracks with its own error in Rust and JS, never a clean end, `Dropped`, or `Cancel`
+- [Dropped sources](/quest/m1/dropped-sources.md) - consumers see the producer's real error on every end path, never `Dropped`
 - [JS bare FIN](/quest/m1/js-bare-fin.md) - a `@moq/net` subscriber aborts a track whose subscribe stream FINs before its declared end, like Rust
 - [Track tail interop](/quest/m1/track-tail-interop.md) - a Rust publisher ending a track with a group in flight is read to its end by the JS subscriber, and the reverse, in `just test interop`
+- [Interop flakes](/quest/m1/interop-flakes.md) - the interop harness passes with other runs sharing the machine
 - [Signal.race cleanup](/quest/m1/signal-race.md) - `Signal.race` releases its signal listeners when its result loses a race
 - [Origin narrowing](/quest/m1/origin-narrowing.md) - a live origin grant narrows in place and ends the subscriptions it no longer covers, the deafen boundary #2714 asked for
 - [Auth expiry clock](/quest/m1/auth-expiry-clock.md) - moq-auth and the relay hold one fixed expiry deadline and honour the same skew allowance
@@ -60,6 +62,7 @@ transport, benchmark tooling); worktrees isolate commits, not semantics.
 - [Transcode source](/quest/m1/transcode-source.md) - select a rendition the chosen backend can actually decode
 - [Egress rendition pick](/quest/m1/egress-rendition-pick.md) - WHEP and single-track RTMP/FLV serve the best rendition, not the first by name
 - [Keyframe trigger](/quest/m1/keyframe-trigger.md) - an application can ask the built-in capture encoder for a keyframe
+- [Video keyframe flag](/quest/m1/video-keyframe-flag.md) - encoded video marks its keyframes, so a requested cut never forces an extra one after a cadence keyframe
 - [QoS](/quest/m1/qos/README.md) - broadcast health: relay starvation and timeliness histograms, and client stats broadcasts from publishers and viewers
 - [Drain](/quest/m1/drain/README.md) - relay restarts drain sessions over GOAWAY instead of hard-dropping them
 - [Transport upgrade](/quest/m1/transport-upgrade/README.md) - a session that came up over WebSocket moves to QUIC once the QUIC dial lands, handing over at a group boundary

quest/m1/dropped-sources.md

@@ -0,0 +1,27 @@
+# [M] Consumers see the producer's real error, never Dropped
+
+## Goal
+
+A track or broadcast that ends because its source ended reports the source's
+own error to every consumer, locally and across a relay. `Dropped` means only
+that a handle was dropped without an end, which a correct producer never does.
+#4179 fixed one path (a revoked upstream subscription now reads
+`Unauthorized`); the rest still surface `Dropped`.
+
+## Plan
+
+- Known sources, from #4179: a source closing, a route leaving the origin's
+  table, and a withdrawn source broadcast. Find each place a consumer can
+  observe `Dropped` and make the ending side carry its real error (an explicit
+  `abort` or a preserved cause), at the source rather than by remapping at the
+  consumer.
+- moq-transport: a `PUBLISH_DONE` carrying Unauthorized arrives as
+  `Error::Remote(1)`. Map it to the same error lite reports.
+- Regression tests per path, each failing on `Dropped` today, in-process and
+  over a mock session.
+
+Public API: none expected; error values consumers observe change. Wire: none.
+
+## Related
+
+- [#4179](https://github.com/moq-dev/moq/pull/4179) - fixed the revoked-upstream path

quest/m1/interop-flakes.md

@@ -0,0 +1,23 @@
+# [S] Interop harness runs clean in parallel
+
+## Goal
+
+`just test interop --all` passes reliably while other harness runs share the
+machine. Two known flakes: concurrent Nix shells reserve the same port because
+each keeps its reservations under its own `TMPDIR`, and the browser driver's
+pause click is sometimes blocked by the canvas (`js -> js`).
+
+## Plan
+
+- Port reservations live under one root shared by every shell (not
+  `TMPDIR`), or ports come from the OS (bind to 0 and pass the result). Prefer
+  whichever removes the reservation file entirely.
+- The pause control is driven in a way the canvas cannot intercept (an API or
+  keyboard path, or waiting for the element to be actionable), not a retry.
+- Prove it by running two `--all` harnesses at once, several times.
+
+Public API: none. Wire: none.
+
+## Related
+
+- [#4181](https://github.com/moq-dev/moq/pull/4181) - where both flakes were seen

quest/m1/video-keyframe-flag.md

@@ -0,0 +1,24 @@
+# [S] Encoded video knows its keyframes
+
+## Goal
+
+`moq_video::encode::Encoded` says whether an access unit is a keyframe, so the
+capture `Control::cut()` throttle counts every keyframe, including the
+encoder's own GOP cadence. Today it sees only forced and opening keyframes, so
+a cut requested just after a cadence keyframe still forces another one.
+
+## Plan
+
+- Every backend already knows whether it produced a keyframe; carry it on
+  `Encoded`. Whether that is additive depends on whether `Encoded` is
+  `#[non_exhaustive]`; if it is not, this goes to `dev`.
+- The throttle in the capture driver treats any keyframe as satisfying a
+  pending cut and restarting the spacing window, matching what JS already does.
+- Test with a backend whose GOP produces a keyframe right before a requested
+  cut, asserting no extra keyframe.
+
+Public API: one field or accessor on `Encoded`. Wire: none.
+
+## Related
+
+- [#4184](https://github.com/moq-dev/moq/pull/4184) - the `Control::cut()` this completes