fix(cog-pose-estimation): emit frames under default config (ADR-159 A1)

pose_v1 has no confidence head, so infer() emits a constant 0.185 per
frame. The config default_min_confidence was 0.3 and the runtime gates
on confidence >= min_confidence, so a default install silently emitted
ZERO pose.frame events while health reported healthy.

- Add inference::MODEL_TYPICAL_CONFIDENCE (0.185, the validation PCK@50)
  as the single published per-frame confidence.
- Pin default_min_confidence() to MODEL_TYPICAL_CONFIDENCE so a default
  install clears its own gate and emits.
- Warn at run.started when min_confidence exceeds the model typical
  confidence (disclosed, not silent); document the trade-off in the
  config field, the JSON schema, and inference.rs.

Failing-on-old test: default_config_emits_frames_with_real_model
(with old 0.3 it panics: "default install would emit zero pose.frame
events").

Co-Authored-By: claude-flow <ruv@ruv.net>

v2/crates/cog-pose-estimation/cog/config.schema.json

@@ -26,8 +26,8 @@
       "type": "number",
       "minimum": 0,
       "maximum": 1,
-      "default": 0.3,
-      "description": "Drop frames where the inferred pose confidence is below this threshold."
+      "default": 0.185,
+      "description": "Drop frames where the inferred pose confidence is below this threshold. pose_v1 has no confidence head, so every frame carries the model's published per-frame confidence (0.185 = validation PCK@50); the default is pinned to that value so a default install actually emits frames. Raising it above 0.185 suppresses ALL pose.frame events (the runtime warns when this happens)."
     }
   },
   "required": ["model_path"]

v2/crates/cog-pose-estimation/src/config.rs

@@ -23,6 +23,13 @@ pub struct CogConfig {
     pub poll_ms: u64,
 
     /// Confidence threshold below which a frame's keypoints are not emitted.
+    ///
+    /// Defaults to [`crate::inference::MODEL_TYPICAL_CONFIDENCE`] (0.185) — the
+    /// model's published per-frame confidence. `pose_v1` has no confidence head,
+    /// so every frame carries this same value; a default above it would silently
+    /// suppress *all* `pose.frame` events while health still reports healthy.
+    /// The runtime warns at `run.started` if this is raised above the model's
+    /// typical confidence rather than dropping frames quietly.
     #[serde(default = "default_min_confidence")]
     pub min_confidence: f32,
 }
@@ -36,7 +43,9 @@ fn default_poll_ms() -> u64 {
 }
 
 fn default_min_confidence() -> f32 {
-    0.3
+    // Pinned to the model's typical/published confidence so a default install
+    // actually emits frames. See `min_confidence` doc and ADR-159 §A1.
+    crate::inference::MODEL_TYPICAL_CONFIDENCE
 }
 
 impl CogConfig {

v2/crates/cog-pose-estimation/src/inference.rs

@@ -27,6 +27,16 @@ pub const INPUT_SUBCARRIERS: usize = 56;
 pub const INPUT_TIMESTEPS: usize = 20;
 pub const OUTPUT_KEYPOINTS: usize = 17;
 
+/// The model's typical self-reported confidence. `pose_v1` has **no confidence
+/// head** (the head emits 34 keypoint coordinates only), so per-frame confidence
+/// is not available from the network. This is the validation-set PCK@50 (18.5%)
+/// the training run reported, used as the published per-frame confidence floor.
+///
+/// Surfaced as a public constant so the runtime can warn when a configured
+/// `min_confidence` threshold exceeds it — otherwise a default install would
+/// silently emit zero `pose.frame` events while health reports healthy.
+pub const MODEL_TYPICAL_CONFIDENCE: f32 = 0.185;
+
 #[derive(Debug, Clone)]
 pub struct CsiWindow {
     pub data: Vec<f32>, // length INPUT_SUBCARRIERS * INPUT_TIMESTEPS
@@ -283,12 +293,15 @@ impl InferenceEngine {
         let out = model.net.forward(&t)?; // [1, 34]
         let flat: Vec<f32> = out.flatten_all()?.to_vec1()?;
         // Confidence from pose_v1 is a published constant rather than per-frame —
-        // the trained model didn't emit a confidence head. Use the validation-set
-        // PCK@50 (18.5%) as the published self-reported confidence so downstream
-        // consumers can gate display decisions on it.
+        // the trained model has no confidence head (the head emits 34 keypoint
+        // coordinates only), so a real per-frame value is genuinely unavailable.
+        // We surface the validation-set PCK@50 (`MODEL_TYPICAL_CONFIDENCE`) as the
+        // honest self-reported confidence. The runtime's `min_confidence` default
+        // is pinned at or below this so a default install actually emits frames
+        // (and warns if an operator raises the threshold above the model's reach).
         Ok(PoseOutput {
             keypoints: flat,
-            confidence: 0.185,
+            confidence: MODEL_TYPICAL_CONFIDENCE,
         })
     }
 }

v2/crates/cog-pose-estimation/src/main.rs

@@ -113,6 +113,18 @@ fn cmd_run(
     let cfg = CogConfig::load(&config_path)?;
     emit_event(&Event::run_started(COG_ID, &cfg));
 
+    // Disclosure: pose_v1 has no confidence head, so every frame carries the
+    // same `MODEL_TYPICAL_CONFIDENCE`. A `min_confidence` above that silently
+    // suppresses *all* pose.frame events. Warn loudly rather than drop quietly.
+    if cfg.min_confidence > cog_pose_estimation::inference::MODEL_TYPICAL_CONFIDENCE {
+        tracing::warn!(
+            min_confidence = cfg.min_confidence,
+            model_typical_confidence = cog_pose_estimation::inference::MODEL_TYPICAL_CONFIDENCE,
+            "configured min_confidence exceeds the model's typical confidence; \
+             no pose.frame events will be emitted until this is lowered"
+        );
+    }
+
     let engine = InferenceEngine::with_adapter(adapter.as_deref())?;
     if engine.is_calibrated() {
         tracing::info!("per-room calibration adapter loaded");

v2/crates/cog-pose-estimation/tests/smoke.rs

@@ -172,3 +172,56 @@ fn manifest_roundtrips() {
     assert_eq!(back.id, "pose-estimation");
     assert_eq!(back.version, "0.0.1");
 }
+
+/// ADR-159 §A1 — the default-config min_confidence threshold must not silently
+/// suppress every `pose.frame`. With the old `default_min_confidence()=0.3` and
+/// the model's per-frame confidence pinned at 0.185, the runtime gate
+/// (`out.confidence >= cfg.min_confidence`) never fired, so a default install
+/// emitted ZERO frames while health reported healthy. This asserts the default
+/// install actually clears its own gate.
+#[test]
+fn default_config_emits_frames_with_real_model() {
+    use cog_pose_estimation::config::CogConfig;
+
+    // A minimal config (only the required model_path) exercises every
+    // `#[serde(default)]` path — i.e. the *default* install threshold.
+    let cfg: CogConfig =
+        serde_json::from_value(serde_json::json!({ "model_path": "pose_v1.safetensors" }))
+            .expect("default config parse");
+
+    // Real model when present; stub otherwise. Either way the per-frame
+    // confidence the runtime gates on must clear the default threshold,
+    // OR (stub case) the gate must still let the model's typical confidence
+    // through. We assert against the same value the runtime emits.
+    let weights = std::path::Path::new("cog/artifacts/pose_v1.safetensors");
+    let engine = if weights.exists() {
+        InferenceEngine::with_weights(Some(weights)).expect("load real weights")
+    } else {
+        InferenceEngine::new().expect("engine init")
+    };
+
+    // Core regression assertion (fails on the old `default_min_confidence()=0.3`):
+    // the default threshold must not exceed the model's published per-frame
+    // confidence (0.185), which is the exact value `infer()` emits for the real
+    // model. With 0.3 the runtime gate `out.confidence >= min_confidence` never
+    // fired → zero pose.frame events on a default install.
+    assert!(
+        cfg.min_confidence <= cog_pose_estimation::inference::MODEL_TYPICAL_CONFIDENCE,
+        "default min_confidence {} exceeds model typical confidence {} — \
+         a default install would emit zero pose.frame events",
+        cfg.min_confidence,
+        cog_pose_estimation::inference::MODEL_TYPICAL_CONFIDENCE
+    );
+
+    // End-to-end: when the real model is loaded, the value it actually emits
+    // must clear the default gate (i.e. the runtime would emit this frame).
+    if engine.backend().starts_with("candle-") {
+        let out = engine.infer(&SyntheticInput.as_window()).expect("infer");
+        assert!(
+            out.confidence >= cfg.min_confidence,
+            "default install must emit: infer confidence {} < default min_confidence {}",
+            out.confidence,
+            cfg.min_confidence
+        );
+    }
+}