ipc: a seed_event method, step-up gated, refused by the store (V-518)

The pattern detector needs four events for one action+object spread by at
least two hours before it proposes a routine. The only writer in the tree is
a fact write at time.Now(), so V-43, V-46, V-247 and V-254 all stopped at the
same missing step. This is the wire half of the seam that unblocks them.

The request takes a fact — key, value, timestamp — not an event, so
pattern.Extract runs for real on the daemon side and a key the extractor
ignores seeds nothing. The response says which of those happened, because a
caller that assumed a seed always yields an event would read four silent
successes as a broken detector.

AuthStepUp, the same rung as mutating the tool allowlist, and not because
backdating is privileged in the usual sense: every other write records when
something happened and this one asserts it. StoreAPI refuses outright — the
method needs the daemon's detect-and-propose step, and a direct store caller
would write a fact and quietly skip it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011x5DgnExQ5XZy8TZPs5bot

internal/ipc/api.go

@@ -184,6 +184,48 @@ type CaptureTaskResp struct {
 	Promoted bool `json:"promoted,omitempty"`
 }
 
+// SeedEventReq — write one fact at a caller-supplied timestamp and run the
+// pattern path over it, so a recurring routine can be produced on demand
+// instead of over real days (Vikunja #518).
+//
+// This is the ONLY backdating write path in the tree, and it exists for one
+// reason: the detector needs four events spread over hours before it proposes
+// anything, so V-43, V-46, V-247 and V-254 could not be verified against a
+// running daemon at all. A store fixture would have exercised the detector
+// without the wiring those tasks doubt.
+//
+// Two things hold it shut. It is AuthStepUp in the authority table, the same
+// rung as mutating the tool allowlist. And mavend refuses it outright unless
+// started with -allow-seed, so a box nobody is testing carries no live
+// backdating path even for a caller who cleared the gate.
+//
+// Key and Value are a fact, not an event: extraction runs for real, so a key
+// the extractor ignores seeds nothing and says so. That is deliberate — a
+// seam that accepted action and object directly would let QA prove a detector
+// against events no utterance could ever produce.
+type SeedEventReq struct {
+	Key   string    `json:"key"`
+	Value string    `json:"value"`
+	Ts    time.Time `json:"ts"`
+}
+
+// SeedEventResp — what the seed produced. Extracted is false when the fact was
+// written but yielded no event, which is the extractor declining rather than a
+// failure. Proposed is true only when this seed completed a pattern; the first
+// three seeds of a run return false with no routine.
+type SeedEventResp struct {
+	FactID    int64 `json:"fact_id"`
+	EventID   int64 `json:"event_id,omitempty"`
+	Extracted bool  `json:"extracted"`
+	Action    string `json:"action,omitempty"`
+	Object    string `json:"object,omitempty"`
+	Proposed  bool   `json:"proposed"`
+	RoutineID int64  `json:"routine_id,omitempty"`
+	// IntervalDays — the median the detector settled on, echoed so QA can
+	// check it against the spacing it asked for.
+	IntervalDays float64 `json:"interval_days,omitempty"`
+}
+
 // IngestMailReq — one message a mail reader has fetched, handed to core for
 // extraction (Vikunja #246).
 //