feat(domain): Reconciliation -- how a merged transcript came about (ADR-034)

Status (reconciled / single_engine / skipped), exact counts, and a bounded list of
contested spots (changed or unsure) with a position and both readings.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/domain/domain.go

@@ -129,6 +129,50 @@ type Transcription struct {
 	Segments     []Segment
 	Endpoint     string
 	AudioSeconds float64
+	// Reconciliation is set when two engines transcribed the same audio and a local
+	// model chose between their disagreements (ADR-034). Nil for a single engine.
+	Reconciliation *Reconciliation
+}
+
+// ReconcileStatus says what became of an attempt to merge two transcripts.
+type ReconcileStatus string
+
+const (
+	// ReconcileDone: both engines produced text and the disagreements were resolved.
+	ReconcileDone ReconcileStatus = "reconciled"
+	// ReconcileSingle: only one engine produced text, so there was nothing to merge.
+	ReconcileSingle ReconcileStatus = "single_engine"
+	// ReconcileSkipped: both engines produced text but the model could not be used;
+	// the base text stands, unreconciled.
+	ReconcileSkipped ReconcileStatus = "skipped"
+)
+
+// ContestedSpot is a place the engines disagreed that a reader may want to check
+// against the audio: one the model changed, or one it was unsure about.
+type ContestedSpot struct {
+	Seconds float64 `json:"seconds"` // roughly where in the recording
+	Base    string  `json:"base"`    // what the base engine heard
+	Alt     string  `json:"alt"`     // what the other engine heard
+	Used    string  `json:"used"`    // "base" or "alt": the reading now in the text
+	Unsure  bool    `json:"unsure"`  // the model could not decide; the base was kept
+}
+
+// Reconciliation records how a merged transcript came about, so the page can say so
+// plainly and the user can check the uncertain spots. The counts are exact; Contested
+// is bounded.
+type Reconciliation struct {
+	Status       ReconcileStatus `json:"status"`
+	Reason       string          `json:"reason,omitempty"` // why single_engine or skipped
+	Base         string          `json:"base"`             // engine whose text is the base
+	Alt          string          `json:"alt"`
+	Reconciler   string          `json:"reconciler"`
+	Disputes     int             `json:"disputes"`      // places the engines disagreed
+	AutoResolved int             `json:"auto_resolved"` // trivial: compounds, filler words
+	Adjudicated  int             `json:"adjudicated"`   // decided by the model
+	Changed      int             `json:"changed"`       // the alternative's reading was used
+	Unsure       int             `json:"unsure"`        // base kept, flagged
+	Errors       int             `json:"errors"`        // model calls that failed
+	Contested    []ContestedSpot `json:"contested,omitempty"`
 }
 
 // UploadStatus is the state of an uploaded-audio transcription job.