gramps
ec1091a170
"I forgot the VPN" used to create a broadcast on YouTube that nothing ever pushed to: the app looked
live, YouTube held an empty broadcast, and the creator had to work out what happened. Prevention beats
recovery here, so go-live now asks one question first.
- `Services/IngestProbe.cs` — `IIngestProbe` + `TcpIngestProbe`: parse the RTMP URL, connect to the host
(rtmp → 1935, rtmps → 443) with a 2 s timeout. Any failure answers "not reachable"; the point is a
fast unambiguous answer, not a diagnosis.
- `MainViewModel.IngestPreflightAsync` runs **before the first API call** whenever a cached ingest URL
exists; on a first run it probes once the stream is resolved, still before any broadcast is created.
A false answer logs, tells the creator ("Nothing was created on YouTube…"), and rolls the session
back — nothing to clean up on YouTube.
- The probe is a test seam (`IngestProbeOverride`) like the camera and chroma ones.
Tests: `IngestPreflightTests` — unreachable aborts, reachable continues, URL parsing (rtmp/rtmps,
garbage), and the probe against **real sockets**: a listening port answers true, the same port closed
answers false and does so fast. FAST gate: 547 passed, 0 failed, 0 warnings.
69 lines
5.4 KiB
Markdown
69 lines
5.4 KiB
Markdown
# TASK 32 — Stream resilience (queued 2026-09-01 — merges the orphaned TASK 2 resume clause into the pills/signs architecture)
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> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
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**Goal:** a dropped stream heals itself when physically possible, tells the truth when it isn't, and
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gets the creator back on air in one click. The ON-AIR sign + primary button in the top bar are the
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surface — they already mean "reality" (pills = intent, lights = reality, TASK 18/30); reality just
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isn't two-state. Resumption of a completed broadcast is explicitly **out of scope** (impossible via
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the API — creator ruling 2026-09-01): no lying in the copy.
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**Slices (one integration test each, in order):**
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1. ✅ **Blip retry** (shipped 2026-11-05) — app-side encoder restart: push dies while live (ProcessFailed / stdin
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backpressure death) → bounded-backoff relaunch (2s/5s/10s, N attempts) against the cached
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constant reusable-stream ingest URL. Success = push running again while the broadcast is still
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live; viewers never know. Fixes the map's stale "ffmpeg does reconnect" claim (corrected
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2026-09-01: reconnect flags are input-side only). Test: fake process fails once then starts →
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pump recovers without surfacing to the VM.
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**Shipped:** `Services/StreamRetryPolicy.cs` (immediate, +1 s, +2 s, +3 s — minimum waits, because
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YouTube's grace is short), `Services/StreamRecovery.cs` (the loop, with the audio pipe recreated per
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attempt because its single-instance server is unusable after the old client died), and
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`FramePump.EncoderFailed` separating a dead push (recoverable) from a fatal pump fault. Each episode
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reports into the left panel's alert stack; a reconnect that lands on a **complete** broadcast is
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reported as such instead of showing a live sign over a dead stream. Tests: `StreamRecoveryTests`.
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2. 🔶 **Poll-driven sign — NO invented countdown** (spec revised 2026-11-05, creator challenge:
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*"I really don't think that's going to be a constant — it's going to depend on so many variables, some
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that are dark to us"*). The original plan was a measured grace constant and a countdown to YouTube's
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cutoff. **Dropped**: YouTube's cutoff is server-side and depends on things we cannot observe
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(ingest node health, prior stream quality, region, load), so any pinned number is a guess wearing a
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timer. What ships instead:
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- **Amber RECONNECTING** in the top bar, with **measured** facts only: elapsed time and attempt
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count ("RECONNECTING · 0:12 · attempt 2 of 4"). No countdown.
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- **The status poll speeds up** while recovering (30 s → ~4 s) and drives the truth. Signals used,
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cheapest first: `liveBroadcasts.list` `status.lifeCycleStatus` (authoritative `complete`),
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`liveStreams.list` `status.streamStatus`/`healthStatus` (is the push being received), and the
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**`chatEndedEvent`** YouTube already puts in the chat feed we poll — free, and previously skipped.
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- At `complete`: **red OFF AIR**, stop retrying, and (slice 3) offer **Back on air**.
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Test: a fake status provider drives the sign through live → reconnecting → off air; a `chatEndedEvent`
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triggers an immediate status check rather than a decision of its own.
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3. ☐ **One-click Back on air** — the relabeled button fires the existing go-live path with saved
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`Broadcast.*` + cached stream, dialog skipped: new broadcast, new VOD (accepted cost, stated
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in-product). Test: seeded saved form + fake stream service → click creates + pushes, no dialog.
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4. ✅ **Crash-safe recording** (shipped 2026-11-05) — fragmented MP4 on the record block (`-movflags
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frag_keyframe+empty_moov+default_base_moof`): plain MP4's trailing moov atom means a power loss
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kills the WHOLE file. Rename-on-stop unchanged. Closes the TASK 18 "MKV as an option" design-note
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remnant (fragmented MP4 chosen over MKV: single container, YouTube-upload-native — verify player/
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editor tolerance, cite the research). Test: `Args_RecordBlock_IsFragmentedMp4_SoACrashKeepsTheFile` — the flags are on the record block and
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absent from the streaming block. Verified by construction only: the file still needs one real
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interrupted-take check on Windows (kill ffmpeg mid-recording, play the result).
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5. ✅ **Pre-flight** (shipped 2026-11-05) — before broadcast insert, one TCP probe to the ingest host:1935 (~2s timeout).
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Unreachable → Error toast, no insert, no ghost broadcast ("check VPN/network"). The "forgot the
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VPN" story, solved as prevention instead of recovery. Test: fake probe failure aborts go-live before any API call.
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**Shipped:** `Services/IngestProbe.cs` (`IIngestProbe` + `TcpIngestProbe`, 2 s timeout, rtmp→1935 /
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rtmps→443) and `MainViewModel.IngestPreflightAsync`, called BEFORE the first API call whenever a
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cached ingest URL exists (first run probes after resolving the stream, still before any broadcast is
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created). Tests: `IngestPreflightTests` — unreachable aborts, reachable continues, and the probe is
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exercised against real sockets (a listening port answers true, the same port closed answers false
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quickly).
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### Design decisions
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- **The sign is the status, the button is the action** — no new chrome, no log lines, no spinners.
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- **Honest windows:** countdown = observed grace; at zero we say OFF AIR, we don't pretend to reconnect.
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- **Why us > incumbents:** constant reusable stream + persisted form make retry/restart cheap; OBS
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shows a reconnecting log line and Streamlabs silently dies.
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