ISR/CLAUDE.md

CLAUDE.md

Guidance for Claude Code when working in this repository.

Rules

• Always update README.md when user-facing behaviour changes (flags, endpoints, Docker setup, features), and commit it in the same commit as the code change. README is the external reference; CLAUDE.md documents internals.
• Run python -m pytest tests/ after changing isr.py or web.py (tests cover the recorder and the loud-section detector).

Files

File	Purpose
isr.py	Recorder: streams (Icecast/HTTP) + ALSA soundcards, time-aligned file splits
web.py	Archive browser: HTTP server, file listing, RMS loudness analysis, cut/delete
webui.html	Single-page UI (HTML/CSS/JS), loaded by web.py at startup — must sit next to web.py and be copied in the Dockerfile
config.ini	Recording sources; copy from config.example.ini. [general] gives defaults, every other section is a source (type = stream or type = soundcard)
asound.conf	dsnoop device shared_mic so ISR and other ALSA apps can share a soundcard

Commands

python isr.py [config.ini]        # recorder; --list-devices to list ALSA inputs
python web.py                     # web UI on :8080 (--dir, --port, --margin, --min-gap, --min-duration, --analyses-dir)
python -m pytest tests/           # test suite
docker compose up -d / down       # web UI mapped to host port 8050

Dependencies: requests (streams), numpy + soundfile (FLAC output and FLAC analysis/clips — both optional, code degrades gracefully).

Code map

web.py:

• Detection: _compute_rms_windows_wav() / analyze_flac() produce 100 ms RMS windows → _noise_floor_db() estimates the rolling floor → _loud_sections() emits scored sections → _package_result() shapes the /api/analyze payload.
• Clips: _api_clip() validates params, _clip_wav() / _clip_flac() stream the decoded slice, _wav_header() builds the 44-byte PCM header.
• Live headers: _live_wav_header(), _live_flac_header() (+ _flac_frame_samples(), CRC-8 verified).
• Serving: _stream() (Range support), _copy_to_response(), _safe_path() (path traversal guard).

webui.html (one <script> block):

• Clip review: clipQueue/clipCursor globals, playClip(), playFileSection(), hideClipBar(); markup is the #clip-bar div.
• Day review: dayHighlights() builds dayActiveSections (chronological); jumpToDaySection() arms the queue.
• J/K: single document-level keydown listener — clip queue takes priority, in-player currentTime stepping is the fallback when no queue is armed.
• Analysis: fetchAnalysis() (session analysisCache), analyse() (per-row render), cachedParamsMatch() (autoload guard).

Verifying changes

• python -m pytest tests/ covers the recorder (test_isr.py) and the detector (test_web.py).
• There is no JS toolchain and no node on the dev box. After editing webui.html, cross-check every getElementById('x') against an id="x" declaration, and smoke-test endpoints.
• Endpoint smoke pattern: write a temp WAV/FLAC with a known loud burst, subclass web._Handler with recordings_dir/analyses_dir pointing at the temp dir, serve web._Server(('127.0.0.1', 0), H) in a daemon thread, then hit /api/analyze and /api/clip with urllib — assert section start/score and that Content-Length == len(body) == 44 + frames × channels × 2.
• Dev box is Windows / PowerShell 5.1. Multi-line commit messages: use the Bash tool with git commit -F - <<'EOF' — PowerShell here-strings containing quotes get mangled into separate arguments.

Non-obvious internals

• Recorder/web coupling is one file: RecorderManager atomically writes recordings/status.json every 2 s listing in-progress files; deleted on clean shutdown. web.py reads it to show REC badges and to refuse analyse/cut/delete on active files. In-progress WAV/FLAC headers are unfinalized, so durations are not read for active files.
• Stream splits: OGG/Opus/FLAC codec headers are extracted from the first ~16 KB of each connection and prepended to every split file so each file plays standalone. A new file is always opened on reconnect (gap in stream). MP3/AAC need no headers.
• Split timing: files split at clock-aligned boundaries (get_next_split_time()), e.g. split_minutes = 60 → on the hour.
• ALSA: capture spawns arecord as a subprocess, raw PCM read in 100 ms chunks by a thread. Device spec resolution: default → exact hw:X,Y → partial name → fallback to any literal ALSA PCM name (so shared_mic from asound.conf works without appearing in arecord -l).
• Shutdown: SIGTERM is converted to KeyboardInterrupt in main(); RecorderManager.stop() joins all threads against a single shared 25 s deadline to stay inside Docker's stop_grace_period: 30s.
• Loud-section detection is adaptive — do not regress it to an absolute threshold. Per-window dB is compared against a rolling noise floor (NOISE_PERCENTILE-th percentile per NOISE_BLOCK_SECONDS block, min-smoothed over ±2 blocks so events can't raise their own floor; clamped to ≥ MIN_RMS). A section needs margin dB of prominence and carries a score (peak dB above floor) used for ranking. Sections shorter than min_duration (default 0.5 s, after min_gap merging) are discarded — without this, isolated 100 ms pops (clicks, single raindrops) produced thousands of zero-length sections per day. The original fixed RMS threshold flagged every ambience change (passing cars, rain) and produced ~600 useless sections/day — that is why it was replaced. Known limitation: a short (~10 s) swell on a quiet street still flags because the floor blocks are 30 s; the planned fix is an onset/spectral filter or optional Silero VAD, not a higher margin. Tests in tests/test_web.py.
• Analysis params are coupled in five places. CLI --margin/--min-gap/--min-duration → /api/config → UI inputs #margin-input/#min-gap-input/#min-duration-input → /api/analyze query params → cache JSON head keys. Renaming or adding a param means touching all five plus cachedParamsMatch() and the _cached_analysis_params() regex (see the threshold→margin change c84b7d8 and the min_duration addition).
• Analysis cache: results stored as <analyses-dir>/<file>.analysis.json keyed by margin+min_gap+min_duration; orphans pruned at web startup. In Docker the recordings mount is read-only for the web container, so docker-compose layers a read-write ./recordings/analyses bind mount over it. The margin, min_gap, and min_duration keys MUST stay first in the cache JSON — _cached_analysis_params() reads only the first 256 bytes to avoid parsing the large embedded result. Caches written by older detector versions (missing a key) never match and get overwritten on the next analyse.
• Analyze responses: /api/analyze returns rms_display (~800 points), never the full per-window RMS list — the UI doesn't use it and it is ~45x larger.
• Section playback uses clips, not seeks: /api/clip?file&start&end decodes the slice server-side (wave/soundfile) and returns a standalone 16-bit WAV with exact Content-Length (capped at CLIP_MAX_SECONDS), Cache-Control: private so re-listening is free. The UI plays chips/J-K through the bottom clip bar (clipQueue in webui.html); seeking the full file only happens via "Open in file". Rationale (finding): libsndfile writes FLAC without a SEEKTABLE, so a browser seek bisects the whole multi-hundred-MB file with Range requests — seeking big FLACs in <audio> is inherently slow and must not be reintroduced as the primary navigation. Server-side sf.SoundFile.seek() on local disk is fast and frame-accurate.
• HTTP/1.1 keep-alive: _Handler.protocol_version = 'HTTP/1.1'; every response path must set an accurate Content-Length. _copy_to_response() force-closes the connection if it under-delivers (file truncated mid-serve).
• Live playback: for files listed in status.json, /stream/ patches the header on the fly so the browser sees the duration recorded so far and can seek; responses get Cache-Control: no-store. WAV: _live_wav_header derives sizes from the byte count. FLAC: _live_flac_header parses the sample count out of the last frame header in the file tail (CRC-8-verified to reject false sync matches) and rewrites STREAMINFO total_samples — duration is NOT derivable from byte size for FLAC.
• Path safety: every file parameter in web.py goes through _safe_path(), which resolves and verifies the path stays inside the recordings dir.
• dsnoop in Docker: sharing the soundcard requires asound.conf on the host and ipc: host in docker-compose (dsnoop uses shared memory across the container boundary).