Internals

Slides rendering flow

GitHub Edit page

Slides Rendering Flow

Two main paths.

#CLI / terminal

  • src/run/flows/url/slides-output.ts

    • Public construction + orchestration only.

  • slides-output-state.ts

    • Slide timeline state. Waiters. Finalization.

  • slides-output-render.ts

    • Terminal rendering. Inline-image policy. Debug path.

  • slides-output-stream.ts

    • Summary-stream parsing glue.

Rule: keep terminal I/O in render helpers; keep state mutations in the state store.

src/slides/process.ts owns media-tool spawning, deadlines, exit errors, and output collection. Line callbacks, text capture, and binary capture share that lifecycle; OCR uses binary capture to avoid logging recognized text. Ignored stdout is drained so child processes cannot block on a full pipe.

Frame extraction trims decoded input before collecting showinfo and signal statistics. Timestamp conversion uses the explicit input-seek origin, including zero, so pre-seek frames cannot move a later slide backward or cause final duration filtering to discard it.

Completed slide results carry an extractor version in memory and slides.json. Cache validation rejects older/unversioned extraction results, including SQLite copies, so corrected timing regenerates stale frames without invalidating unrelated transcript or summary caches.

src/slides/download.ts owns temporary download directories through success or failure. Failures remove partial output without replacing the original error; successful downloads return cleanup to the caller. Structured yt-dlp progress shares one parser on stdout and stderr, while ordinary percentage/speed/ETA lines remain stderr-only.

Direct-video downloads use a Node stream pipeline for backpressure, file closure, and stream teardown. The download owner also cancels rejected HTTP bodies and aborts settled fetches. src/slides/ingest.ts owns downloaded-file cleanup until cache handoff succeeds, then transfers cleanup to extraction.

#Chrome extension

background/content-script-bridge.ts shares retry/reinjection handling across extraction, seeking, and frame preparation. Only extraction has a message deadline; capture startup and restoration keep their separate recovery policies and self-contained main-world scripts.

  • apps/chrome-extension/src/entrypoints/sidepanel/stream-controller.ts

    • Transport lifecycle.

  • stream-controller-policy.ts

    • Chunk/status terminal state rules.

  • apps/chrome-extension/src/lib/extension-logs.ts

    • Storage queue + flush only.

  • extension-log-format.ts

    • Pure log serialization/truncation.

Rule: push pure status/log logic out of adapters first.

Slide-summary coercion shares paragraph selection and distribution, while retaining separate explicit-summary and fallback text policies. Normal and empty-summary rendering build the same display inputs from live panel state; rendering an empty state does not erase stored Markdown.

#When debugging

  1. Check state transitions before DOM issues.
  2. Check stream policy before transport retry logic.
  3. Check cache/hydration helpers before blaming rendering.