Run pattern detection from the digestion tick, not just voice (#43)

detectPattern only ever fired as a side effect of a voice fact-write, so a
recurring pattern already sitting in history went unnoticed until he
happened to mention it again by voice — the opposite of proactive.

Split the pipeline: extraction (fact -> normalized event) stays where a fact
is written, in voice.go, since it's tied to that write regardless of who's
talking. Detection (events -> stable pattern -> proposed_routines row) moves
into shared code (patterns.go's detectAndPropose) that both the voice path
and the new tick.go:detectPatterns call. The tick runs it every cycle over
every action+object pair on record (store.DistinctEventPairs, added), so a
pattern gets noticed on the daemon's own schedule.

Idempotence and the dismiss-must-stick requirement turned out to already be
handled by the store, not something the tick needs to reinvent:
proposed_routines has UNIQUE(action, object) and CreateProposedRoutine does
ON CONFLICT DO NOTHING, and DismissProposedRoutine flips status in place
without deleting the row. So a pair already proposed, accepted, OR
dismissed is a silent no-op on every later tick — a dismissed pattern can
never resurface, and re-running the scan never spams the /routines page.
Kept the voice-path call (immediate spoken confirmation is a nice feature
UX-wise and is now redundant-but-harmless with the tick, since both paths
share the same guarded detectAndPropose).

Tick-side detection only ever writes a row; it does not notify, ring, or
speak, keeping Maven "not a nag, not autonomous" — the /routines page is
still the only place a proposal becomes visible, and only accepting it
starts producing nudges (fireAcceptedRoutines).

Also fixed the stale vikunja#46 reference in proposed_routines.go — the
TODO it named is what this commit does.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CGeSZxh1DCtRxmFVSYVGvJ

cmd/mavend/patterns.go

@@ -0,0 +1,74 @@
+// mavend/patterns.go — the shared detect+propose step of pattern inference
+// (Vikunja #43). Event *extraction* (fact -> action/object) happens at fact-
+// write time in voice.go's detectPattern, tied to whichever channel wrote the
+// fact. Detection — turning a run of events into a proposed routine — is
+// channel-agnostic: it only needs what's already in the events table, so it
+// runs both right after a voice fact-write (for the immediate "напоминать?"
+// confirmation) and, proactively, from the digestion tick (tick.go's
+// detectPatterns) over every action+object pair on record, not just the one
+// that was just talked about.
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/kami/maven/internal/pattern"
+	"github.com/kami/maven/internal/store"
+)
+
+// detectAndPropose runs the pattern detector over every recorded event for
+// action+object and, if a stable pattern is found and nothing has been
+// proposed/accepted/dismissed for this pair yet, creates a proposed_routines
+// row. Returns (nil, 0, nil) — not an error — whenever there is nothing new
+// to report: too few events, irregular intervals, or a pair that already has
+// a row in any status. That last case is the one that matters most: it is
+// how a routine the owner already DISMISSED stays dismissed forever, because
+// the row survives dismissal (status flips in place, see
+// store.DismissProposedRoutine) and both the Lookup check here and the
+// table's UNIQUE(action, object) constraint refuse to create a second one.
+func detectAndPropose(ctx context.Context, ds *store.Store, action, object string, ts time.Time) (*pattern.ProposedRoutine, int64, error) {
+	events, err := ds.EventsFor(ctx, action, object)
+	if err != nil {
+		return nil, 0, fmt.Errorf("events for %s/%s: %w", action, object, err)
+	}
+	patEvents := make([]pattern.Event, len(events))
+	for i, e := range events {
+		patEvents[i] = pattern.Event{
+			FactID: e.FactID,
+			Action: e.Action,
+			Object: e.Object,
+			Ts:     e.Ts,
+		}
+	}
+	r, err := pattern.Detect(patEvents)
+	if err != nil {
+		return nil, 0, fmt.Errorf("detect %s/%s: %w", action, object, err)
+	}
+	if r == nil {
+		return nil, 0, nil // not enough data or intervals too irregular
+	}
+
+	// Belt: check first so the common "nothing new" case never even attempts
+	// an insert. Suspenders: CreateProposedRoutine's ON CONFLICT DO NOTHING
+	// (backed by the UNIQUE(action,object) constraint) is the actual
+	// guarantee — this Lookup is an optimization, not the source of truth.
+	existing, err := ds.LookupProposedRoutine(ctx, r.Action, r.Object)
+	if err != nil {
+		return nil, 0, fmt.Errorf("lookup proposed routine %s/%s: %w", action, object, err)
+	}
+	if existing != nil {
+		return nil, 0, nil // already proposed, accepted, or dismissed — say nothing
+	}
+
+	id, err := ds.CreateProposedRoutine(ctx, r.Action, r.Object, r.IntervalDays, ts)
+	if err != nil {
+		if errors.Is(err, store.ErrProposedRoutineExists) {
+			return nil, 0, nil // lost a race with another caller — not an error
+		}
+		return nil, 0, fmt.Errorf("create proposed routine %s/%s: %w", action, object, err)
+	}
+	return r, id, nil
+}