Dependency result: Real Tara sit audio and CDN

• Opened: 2026-05-29 when the sit result described synthetic media and no external delivery seam for real recordings.
• Reconciled: 2026-07-18 against the procedural ambient generator, authenticated audio routes, env-gated ElevenLabs guidance seam, Tara player, service tests, and first-sit browser suite. This was a source reconciliation, not a live CDN or voice-provider walk.
• Verdict: partial — Tara now serves a real playable BFF-generated WAV and the sit player fetches, loops, mixes, and honestly reports its availability. A separate guidance route can call the configured voice provider and fails closed without credentials. The player does not consume that guidance route, and no recording catalog, object-store/CDN pipeline, entitlement-aware signed URL, HLS path, or DRM boundary exists in the audited flow.
• Primary specs: apps/oshun/bff/src/tara/ambient-audio.test.ts and apps/oshun/web/e2e/first-tara-sit-deepening.spec.ts.

Result at a glance#

Evidence map#

The solid branch is the shipped first-sit ambient experience. The narrated and recorded-media branches remain separate or external.

Proven observations#

Ambient audio is real and deterministic#

• planAmbientForSession() hashes the session id, chooses a drone root, and derives detuned root/fifth/octave layers with independent slow modulation and a filtered noise bed. synthesizeAmbientWav() emits mono 22.05 kHz, 16-bit PCM with bounded 30–180 second duration and fades.
• The service test proves deterministic plans, different sessions, RIFF/WAVE structure, declared PCM length, non-silent signal energy, fade behavior, and duration clamping. The authenticated route test proves anonymous denial and a playable WAV response.
• The player fetches the route with the member bearer token, converts the body to an object URL, loops it, applies the ambient-mix slider, and exposes loading or unavailable state rather than pretending failed audio is playing.

Voice guidance has an honest provider boundary#

• The BFF exposes opening, midpoint, and closing editorial scripts through a separate guidance route. With both ElevenLabs environment values it invokes the voice-synthesis provider; without them it returns the explicit voice_guidance_not_configured 503.
• This seam is meaningful provider preparation, but TaraSitPlayer currently fetches only ambient.wav. Its transcript, captions, and voice-speed control do not schedule, play, or resample the guidance response.
• The first-sit browser suite exercises player states and the visible ambient unavailable contract using an intercepted media response; it does not judge waveform quality or contact a live voice service.

Boundaries and gaps#

• Procedural ambient is not guided narration. The shipped audible layer is a generated soundscape. It does not contain teacher speech, phase timing, or a narrated curriculum performance.
• A provider route is not player integration. The guidance endpoint can synthesize a phase, but no browser path requests it, synchronizes it with the timer/transcript, or binds voice-speed and caption timing.
• A BFF WAV is not a media delivery platform. Audio is synthesized and cached in process. There is no object-store ingest, global edge cache, byte range policy, adaptive stream, offline media manifest, or bandwidth telemetry.
• Authentication is not paid-content protection. The route requires a member but does not prove per-sit entitlement, short-lived signed URLs, revocation, link leakage resistance, or DRM.
• Automated playback state is not acoustic validation. Tests establish signal energy and UI behavior, not loudness normalization, clipping across the catalog, voice intelligibility, accessibility review, or device output quality.
• Source configuration is not live-provider evidence. No ElevenLabs account, CDN tenant, recording, signed request, regional latency, or production failure recovery was exercised in this reconciliation.

Re-run evidence#

The current shipped boundary is covered by the audio service suite and the first-sit browser suite:

pnpm exec vitest run apps/oshun/bff/src/tara/ambient-audio.test.ts

PW_BROWSER_CHANNEL=chrome pnpm exec playwright test \
  -c apps/oshun/web/playwright.config.ts \
  apps/oshun/web/e2e/first-tara-sit-deepening.spec.ts \
  --workers=1

A green run proves procedural WAV generation, route safety, and current player states. It must not be represented as a narrated sit, live ElevenLabs delivery, signed CDN playback, HLS, DRM, or catalog-wide media quality.

Source trail#

• External-dependency index
• Ambient synthesis
• Ambient and guidance routes
• Audio service test
• Tara sit player
• First-sit browser suite
• First Tara sit result

Cross-references#

• First Tara sit journey
• First Tara sit result
• Tara daily ritual journey
• Offline first-use journey
• External-dependency convention

Open questions#

• Is the target experience procedural ambient, provider-synthesized guidance, human recordings, or a layered combination, and which contract schedules the layers against transcript and captions?
• Which storage/CDN pipeline owns ingest, transcoding, checksums, range/HLS delivery, regional latency, and cache invalidation?
• How will free and paid sits enforce entitlement, short-lived access, revocation, offline licensing, and leak-resistant URLs without overstating DRM?
• What player work binds guidance phases and voice speed while preserving reduced-motion, screen-reader, caption, and offline behavior?
• Which automated media checks cover loudness, clipping, silence, corrupt assets, duration drift, provider failure, and representative real devices?