Phases 2-6: detection, visual timeline, backend hand-off, voiceprints

Phase 2 (call detection): CallDetector using CoreAudio per-process mic
attribution (anarlog technique) — robust start+stop for Zoom/Teams/Signal/Meet,
ignoring our own recording; auto-record toggle. Built; pending live multi-app
confirmation by the user.

Phase 3 (visual timeline foundation): AppAdapter protocol + SpeakerObservation,
TimelineBuilder (hysteresis/overlap/self-merge/aliases), VisualTimeline (schema
1.1), TextRecognizer (Vision OCR), FrameSampler + GridCallAnalyzer (name OCR +
saturated-highlight active-speaker attribution), SignalAdapter, VisualObserver
(window capture; frames released, never saved; minimized->visual_gap, idle != gap).
Synthetic-frame tested; adapter geometry pending real Signal fixtures + live
VisualObserver validation.

Phase 5 (backend hand-off): SparkControlClient (multipart label-merge, sequential,
TLS-skip, 503 Retry-After/413), SessionPackager (chunk plan + WAV slice + timeline
slice/rebase), TranscriptAssembler + SpeakersFile, TranscriptPipeline. Validated
END-TO-END against the live backend (chunk -> label-merge -> speakers.json).

Phase 6 (voiceprints): VoiceprintStore (known_voiceprints, persist named
fingerprints, skip Unknown). Wired: 'Send to backend' button + transcript status,
auto-send toggle (default off) + self-name setting.

All adversarial-review findings fixed. App + XCTest suite build; tests pass.

Ten31Transcripts/Adapters/SignalAdapter.swift

@@ -0,0 +1,31 @@
+import Foundation
+import CoreVideo
+
+/// Signal Desktop adapter. Signal shows avatars/initials with a coloured ring
+/// around the active speaker; names may also be available via the Electron
+/// Accessibility tree (preferred over OCR when we enable it). Geometry/threshold
+/// here are first-pass and will be calibrated against real Signal screenshots.
+struct SignalAdapter: AppAdapter {
+    static let bundleIDs = ["org.whispersystems.signal-desktop"]
+    let adapterVersion = "signal-0.1.0"
+    let preferredFPS = 3
+
+    private let analyzer: GridCallAnalyzer
+
+    init() {
+        var config = GridCallAnalyzer.Config()
+        // Signal tiles are squarish with initials centred; tune with fixtures.
+        config.tileExpandX = 1.6
+        config.tileExpandY = 1.8
+        self.analyzer = GridCallAnalyzer(config: config)
+    }
+
+    func analyze(frame: CVPixelBuffer, at t: TimeInterval) -> [SpeakerObservation] {
+        analyzer.analyze(pixelBuffer: frame, at: t)
+    }
+
+    // Exposed for fixture/synthetic tests.
+    func analyze(cgImage: CGImage, at t: TimeInterval) -> [SpeakerObservation] {
+        analyzer.analyze(cgImage: cgImage, at: t)
+    }
+}