fix(flow): drain trailing audio and harden chunked ASR pipeline

- P0/P1: tail-drain state machine in FlowContinuousCapture with converter flush; FlowSessionManager awaits drain before finalize - P2: FlowCaptureTailDrain policy/tracker, pipeline diagnostics, unit tests - P3: short final chunk merged re-transcription in ChunkedUtterancePipeline - P4: UtteranceTranscriptStitcher composedSafely fallback; preview path parity in LiveDictationController Co-authored-by: Rocky <hkgood@users.noreply.github.com>
2026-07-06 05:13:55 +00:00
parent 537a68552a
commit 8b105430e3
14 changed files with 690 additions and 47 deletions
@@ -0,0 +1,51 @@
+// FlowCaptureTailDrainTests.swift
+// OSGKeyboardTests
+
+import XCTest
+@testable import OSGKeyboardShared
+
+final class FlowCaptureTailDrainTests: XCTestCase {
+
+    private let policy = FlowCaptureTailDrainPolicy(
+        silenceRMSThreshold: 0.02,
+        silenceDurationSeconds: 0.2,
+        maxDrainSeconds: 1.0
+    )
+
+    func testDrainFinishesAfterContinuousSilence() {
+        let tracker = FlowCaptureDrainTracker()
+        let start = Date().timeIntervalSince1970
+        tracker.beginDrain(now: start)
+
+        tracker.noteAudio(samples: [0.001, 0.001], policy: policy, now: start + 0.05)
+
+        let silentAt = start + 0.1
+        let decision = tracker.shouldFinish(policy: policy, now: silentAt + policy.silenceDurationSeconds)
+        XCTAssertTrue(decision.finished)
+        XCTAssertTrue(decision.endedBySilence)
+    }
+
+    func testDrainFinishesAtMaxDurationEvenWithoutSilence() {
+        let tracker = FlowCaptureDrainTracker()
+        let start = Date().timeIntervalSince1970
+        tracker.beginDrain(now: start)
+
+        tracker.noteAudio(samples: [0.5, 0.4], policy: policy, now: start + 0.05)
+        tracker.noteAudio(samples: [0.45, 0.42], policy: policy, now: start + 0.4)
+
+        let decision = tracker.shouldFinish(policy: policy, now: start + policy.maxDrainSeconds)
+        XCTAssertTrue(decision.finished)
+        XCTAssertFalse(decision.endedBySilence)
+    }
+
+    func testRMSDetectsAudibleSamples() {
+        XCTAssertGreaterThan(
+            FlowCaptureDrainTracker.rms(of: [0.2, 0.18, 0.15]),
+            policy.silenceRMSThreshold
+        )
+        XCTAssertLessThan(
+            FlowCaptureDrainTracker.rms(of: [0.001, 0.0005]),
+            policy.silenceRMSThreshold
+        )
+    }
+}