Ship voice enrolment, and report recognition as blocked (#255)

Maven can now be told who someone is. She cannot yet tell who is speaking,
and this commit is careful to say so rather than pretend otherwise.

What works: profiles are enrolled from several deliberately recorded samples,
listed, and deleted. They live in the existing memory_vectors table under a
"speaker:" id prefix, so there is no migration; what that needed was a wider
interface than memory.Store, hence memory.Catalog with ByPrefix and Delete.
Delete is the load-bearing half — a voiceprint someone asked to be rid of has
to actually go, and a search-only store cannot do that. InMemoryStore.Insert
became an upsert by id to match what the persistent store already did.

What does not work, and why it is not faked: there is no speaker-embedding
model on this box. Sixteen ggufs in /mnt/hdd1/llms, all text; no ECAPA, no
x-vector, no titanet, no wespeaker, no .onnx anywhere under /mnt/hdd1. So
newSpeakerEmbedder returns nil, internal/speaker falls back to
speaker.Disabled, Identify answers ErrDisabled, and the daemon logs which
half is off at startup. The plan's "simple MFCC + GMM" floor is refused in
the package comment: MFCC cosine distance detects channel and loudness as
much as voice, and a biometric that is confidently wrong writes false claims
about named people into his memory. A bad floor is worse than none here.

Refused as well, and the reason is in enroll.go's doc comment: the plan asked
for unknown speakers to be enrolled on first interaction with a TTS "кто
это?". There is no request shape in the protocol that could express that.
Taking a biometric of whoever walks past the microphone does it to guests who
are not party to the exchange, and a synthesised question into a room is not
consent from whoever answers.

Authority: enrolment is AuthStepUp, because it is a deliberate sit-down act
that writes a biometric of a named person and never something done by voice
mid-conversation. Deletion is one rung lower at AuthWrite, deliberately
inverting the usual pattern — getting rid of a biometric must never be the
harder half. Listing is AuthRead and never returns the vectors themselves.

Off unless configured: no speaker block means the three methods answer
ErrUnknownMethod, so a default box has no wire path that takes a voiceprint.

make build and make test pass.

Vikunja #255

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TrVSBKe3RFDF4fGYKWYQnX

internal/memory/store.go

@@ -3,6 +3,7 @@ package memory
 import (
 	"context"
 	"sort"
+	"strings"
 	"sync"
 )
 
@@ -19,6 +20,33 @@ type Store interface {
 	Search(ctx context.Context, vec []float32, topK int) ([]Result, error)
 }
 
+// Record is a stored vector read back whole — id, vector and metadata — as
+// opposed to Result, which is a search hit and carries a score instead of the
+// vector.
+type Record struct {
+	ID   string
+	Vec  []float32
+	Meta map[string]string
+}
+
+// Catalog is a Store that can also be enumerated by id prefix and deleted from.
+//
+// Search is not enough for every user of the vector table. Speaker profiles
+// (internal/speaker) need to list exactly their own rows without scoring
+// anything, because listing enrolled voices is not a similarity question, and
+// they need Delete because a voiceprint is data about a person and "forget this
+// voice" has to actually remove it. Note and fact recall use plain Store and are
+// unaffected.
+type Catalog interface {
+	Store
+	// ByPrefix returns every row whose id starts with prefix, in no particular
+	// order. An empty prefix returns everything.
+	ByPrefix(ctx context.Context, prefix string) ([]Record, error)
+	// Delete removes one row by id. Deleting a row that is not there is not an
+	// error: the caller asked for it to be gone and it is gone.
+	Delete(ctx context.Context, id string) error
+}
+
 // item is a single stored vector with metadata.
 type item struct {
 	id   string
@@ -32,14 +60,54 @@ type InMemoryStore struct {
 	items []item
 }
 
+// compile-time check: InMemoryStore satisfies Catalog.
+var _ Catalog = (*InMemoryStore)(nil)
+
 func NewInMemoryStore() *InMemoryStore {
 	return &InMemoryStore{}
 }
 
+// Insert upserts by id, matching the persistent store.MemoryStore: a repeated
+// id replaces the prior row rather than accumulating a second copy. Re-indexing
+// a note is an update, and re-enrolling a voice must replace the old voiceprint
+// rather than leave it searchable.
 func (s *InMemoryStore) Insert(_ context.Context, id string, vec []float32, meta map[string]string) error {
 	s.mu.Lock()
+	defer s.mu.Unlock()
+	for i := range s.items {
+		if s.items[i].id == id {
+			s.items[i] = item{id: id, vec: vec, meta: meta}
+			return nil
+		}
+	}
 	s.items = append(s.items, item{id: id, vec: vec, meta: meta})
-	s.mu.Unlock()
+	return nil
+}
+
+// ByPrefix implements Catalog.
+func (s *InMemoryStore) ByPrefix(_ context.Context, prefix string) ([]Record, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	var out []Record
+	for _, it := range s.items {
+		if !strings.HasPrefix(it.id, prefix) {
+			continue
+		}
+		out = append(out, Record{ID: it.id, Vec: append([]float32(nil), it.vec...), Meta: it.meta})
+	}
+	return out, nil
+}
+
+// Delete implements Catalog.
+func (s *InMemoryStore) Delete(_ context.Context, id string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for i := range s.items {
+		if s.items[i].id == id {
+			s.items = append(s.items[:i], s.items[i+1:]...)
+			return nil
+		}
+	}
 	return nil
 }
 

internal/memory/store_test.go

@@ -2,6 +2,7 @@ package memory
 
 import (
 	"context"
+	"fmt"
 	"math"
 	"testing"
 )
@@ -40,8 +41,9 @@ func TestTopKTruncation(t *testing.T) {
 	s := NewInMemoryStore()
 	ctx := context.Background()
 
+	// Distinct ids: Insert upserts by id, so ten rows need ten ids.
 	for i := 0; i < 10; i++ {
-		s.Insert(ctx, "", []float32{float32(i) / 10, 0, 0}, nil)
+		s.Insert(ctx, fmt.Sprintf("n%d", i), []float32{float32(i) / 10, 0, 0}, nil)
 	}
 
 	results, err := s.Search(ctx, []float32{1, 0, 0}, 3)