feat: add waveform download and storage.

sfm/server.py

@@ -1006,6 +1006,41 @@ def db_set_false_trigger(
     return {"status": "ok", "event_id": event_id, "false_trigger": value}
 
 
+@app.get("/db/events/{event_id}/waveform")
+def db_event_waveform(event_id: str) -> dict:
+    """
+    Return the stored waveform blob for a DB event.
+
+    The response shape is identical to GET /device/event/{index}/waveform so the
+    waveform viewer can consume either source without modification:
+      - total_samples, pretrig_samples, rectime_seconds, samples_decoded
+      - sample_rate
+      - peak_values  (tran, vert, long, micl_psi, peak_vector_sum)
+      - channels     ({"Tran": [...], "Vert": [...], "Long": [...], "Mic": [...]})
+
+    Returns 404 if the event doesn't exist, 422 if the event exists but has no
+    stored waveform (downloaded before waveform storage was implemented).
+    """
+    import json as _json
+    db   = _get_db()
+    found, blob_str = db.get_event_waveform(event_id)
+    if not found:
+        raise HTTPException(status_code=404, detail=f"Event {event_id} not found")
+    if blob_str is None:
+        raise HTTPException(
+            status_code=422,
+            detail=(
+                f"Event {event_id} has no stored waveform. "
+                "Waveform storage requires ACH server v0.11+. "
+                "Re-download the event from the device to backfill."
+            ),
+        )
+    try:
+        return _json.loads(blob_str)
+    except Exception as exc:
+        raise HTTPException(status_code=500, detail=f"Waveform blob corrupt: {exc}") from exc
+
+
 @app.get("/db/monitor_log")
 def db_monitor_log(
     serial:  Optional[str] = Query(None, description="Filter by unit serial"),