Failure Mode Ledger
Purpose
This ledger names failure modes as data-flow problems. The fix should generally move authority or measurement to the right place, not add another after-the-fact filter.
Active Witness Failures
Dead Frequency Band
Symptom:
- emitted symbol is consistently absent or weak on one mic.
Coherent fix:
- calibration marks band unreliable;
- codebook emission avoids it for that path or shared room plan;
- decoder weights it down before trellis selection.
Bad fix:
- classify as normal, then reject “outliers” later.
Symbol Alias
Symptom:
- expected symbol often scores as a neighboring bin.
Coherent fix:
- confusion matrix changes likelihood surface;
- global bin-shift hypotheses are searched as part of the window;
- codebook spacing/order adapts.
Bad fix:
- hard-code a special-case symbol remap without path identity.
Reflection-Dominated Timing
Symptom:
- anchors decode, but delay residuals jump between plausible paths.
Coherent fix:
- preserve multiple delay hypotheses;
- combine with mic/speaker geometry and repeated state;
- report uncertainty to Fensalir/DSP.
Bad fix:
- smooth the jump until it looks calm.
Gain / Clipping
Symptom:
- loopback or mic confidence collapses despite audible witness.
Coherent fix:
- calibration preflight checks clipping/noise floor;
- artifacts record gain state;
- witness amplitude adapts within safe bounds.
Bad fix:
- lower thresholds globally.
Passive Sync Failures
Silence
Symptom:
- passive estimator emits weak or meaningless delay.
Coherent fix:
- confidence falls;
- hybrid emits active watermark/chirp witness.
Bad fix:
- hold stale passive delay as if it were current truth.
Narrowband Music
Symptom:
- PHAT correlation peak is broad or ambiguous.
Coherent fix:
- passive confidence remains advisory;
- active witness or longer evidence window takes authority.
Bad fix:
- pretend a low-frequency beat gives microsecond timing.
Audio Actuator Failures
Delay Corrected, Drift Ignored
Symptom:
- streams align briefly and then walk apart.
Coherent fix:
- separate delay and SRO loops;
- drive ASRC/fractional delay continuously.
Bad fix:
- periodically snap delay back with audible discontinuity.
Actuator Chases Source Motion
Symptom:
- moving speaker/mic looks like sample-rate drift.
Coherent fix:
- slow SRO loop uses long-term clock evidence;
- fast TDOA/source motion remains separate.
Bad fix:
- one smoothing constant for everything.
Camera Failures
Advertised FPS Lies
Symptom:
- device reports 60/120 fps but delivers less.
Coherent fix:
- measure actual cadence after warm-up;
- record topology/control settings;
- treat measured cadence as truth.
Bad fix:
- trust media type advertisements.
Shared USB Collapse
Symptom:
- one device’s cadence drops when another device appears.
Coherent fix:
- topology/cadence benchmark;
- distribute devices across controllers/hosts;
- record known bad neighborhoods.
Bad fix:
- add buffering and call latency acceptable.
JSON Bridge Becomes Production
Symptom:
- diagnostic frame events are relied on for live six-camera ingest.
Coherent fix:
- promote probe logic into native worker ABI;
- payload handles enter runtime/reservoir.
Bad fix:
- optimize JSON parsing.
Fusion Failures
CPU Pixel Furnace
Symptom:
- managed code demosaics/converts/processes every camera frame.
Coherent fix:
- push feature extraction/upload into Fensalir GPU path;
- keep CPU metadata small.
Bad fix:
- add worker threads until the thermal budget files a complaint.
Parallel Stable Track Owners
Symptom:
- Mimir and Fensalir both maintain stable visual/acoustic track identity.
Coherent fix:
- Mimir owns observations;
- Fensalir temporal evidence reservoir owns tracks after lowering.
Bad fix:
- add id synchronization glue.
Network Failures
Transport Timestamp Worship
Symptom:
- Raven/phone timing is derived from packet arrival time.
Coherent fix:
- remote receiver decodes codebook anchors locally;
- network time is coarse metadata only.
Bad fix:
- add latency compensation constants per sender.