Turn a mail into task candidates, and into nothing else (#246)

The extraction half. internal/email.Extractor asks the resident Qwen3-1.7B,
under a GBNF grammar, what one message requires of him, and returns at most
three short candidates with an optional date.

Everything it can produce is a row in `tasks` with status "candidate",
written through the intake seam #130 built for exactly this (Source
"email:<mailbox>", Evidence = the subject line). No reminder, no fact, no
note, no calendar event. That bound is the design: a reminder FIRES, so a
1.7B misreading "встреча была в четверг" as a future appointment would wake
him up about it, whereas a wrong candidate is a line he dismisses in one
click. A due date the model read out of the mail is stored on the candidate,
where no scheduler reads it — the review page sorts by it. Relative wording
("до пятницы") is deliberately left in the text rather than resolved to a
date the model would get wrong.

The prompt is written against the two things a small model does here: it
summarises when asked to extract, and it invents an obligation out of a
polite closing line. Hence the demand for a verb phrase, and an explicit
empty array — most mail contains no task, and a model with no way to say
"nothing" says something.

Wiring: core owns extraction because llama-server lives in core's process,
so the reader hands messages over a new ipc.MethodIngestMail. It is a Server
hook (like StepUp/UnlockFn), not a CoreAPI method — not a store operation,
and no CoreAPI implementation should have to carry it. The hook stays nil
without an `email` config block or without a llama-server phraser, so the
method answers ErrUnknownMethod: off unless configured, twice over. There is
no keyword fallback on purpose — "the subject became a task" is a mailbox
rendered as a to-do list, not extraction.

Privacy: junk is refused before the model is called, mail text is never
search input, extraction errors carry byte counts rather than the reply, the
stored evidence is a truncated subject, and the log line names the mailbox
and the UID only.

internal/ipc/api.go

@@ -138,6 +138,44 @@ type CaptureTaskResp struct {
 	Created bool  `json:"created"`
 }
 
+// IngestMailReq — one message a mail reader has fetched, handed to core for
+// extraction (Vikunja #246).
+//
+// The mail reader (cmd/mavmaild) holds the IMAP credential and core never sees
+// it, the same split mavpoll uses for the zenmoney token. What crosses this
+// boundary is only the message text, because extraction runs on the resident
+// model and llama-server lives inside core's process.
+//
+// Body is already plaintext and truncated by internal/email; core does not
+// re-parse MIME and never stores the body. Junk means the reader's header
+// filter already classified the message as bulk — core is told rather than
+// asked, so a junk message can be counted without a model call.
+//
+// This method is available only when core has an email block configured AND a
+// llama-server phraser; otherwise it answers ErrUnknownMethod, which is what
+// "off unless configured" looks like at the wire.
+type IngestMailReq struct {
+	Mailbox string `json:"mailbox"`
+	UID     uint32 `json:"uid"`
+	From    string `json:"from,omitempty"`
+	Subject string `json:"subject,omitempty"`
+	Date    string `json:"date,omitempty"`
+	Body    string `json:"body,omitempty"`
+	Junk    bool   `json:"junk,omitempty"`
+}
+
+// IngestMailResp — what core did with the message. TaskIDs are the rows
+// CaptureTask returned; Created counts the ones that were new (a re-read
+// mailbox dedupes to Created=0). Skipped is set when nothing was asked of the
+// model at all — junk, or an empty message.
+//
+// Nothing here echoes the mail back. The reader logs counts.
+type IngestMailResp struct {
+	TaskIDs []int64 `json:"task_ids,omitempty"`
+	Created int     `json:"created"`
+	Skipped bool    `json:"skipped,omitempty"`
+}
+
 type listTasksReq struct {
 	Status string `json:"status"` // "" all | "live" | candidate|open|done|dropped
 }

internal/ipc/client.go

@@ -448,6 +448,17 @@ func (c *Client) SetTaskStatus(ctx context.Context, id int64, status string, ts
 	return c.call(ctx, MethodSetTaskStatus, setTaskStatusReq{ID: id, Status: status, Ts: ts}, nil)
 }
 
+// IngestMail hands one fetched message to core for extraction. ErrUnknownMethod
+// means core has no email block configured — the caller should stop asking, not
+// retry.
+func (c *Client) IngestMail(ctx context.Context, req IngestMailReq) (IngestMailResp, error) {
+	var r IngestMailResp
+	if err := c.call(ctx, MethodIngestMail, req, &r); err != nil {
+		return IngestMailResp{}, err
+	}
+	return r, nil
+}
+
 func (c *Client) DismissProposedRoutine(ctx context.Context, id int64) error {
 	return c.call(ctx, MethodDismissProposedRoutine, dismissProposedRoutineReq{ID: id}, nil)
 }

internal/ipc/ipc_test.go

@@ -565,3 +565,36 @@ func mustJSON(v any) []byte {
 	}
 	return b
 }
+
+// TestIngestMail_OffUnlessConfigured — with no IngestMailFn set (the default,
+// and what an unconfigured core looks like) the method does not exist. A mail
+// reader gets a refusal it can act on rather than a silent success.
+func TestIngestMail_OffUnlessConfigured(t *testing.T) {
+	_, _, cli, _ := newServerWithStore(t)
+	if _, err := cli.IngestMail(context.Background(), IngestMailReq{Mailbox: "INBOX", UID: 1}); !errors.Is(err, ErrUnknownMethod) {
+		t.Fatalf("IngestMail error = %v, want ErrUnknownMethod", err)
+	}
+}
+
+// TestIngestMail_Hook — when the daemon wires the hook, the message crosses the
+// boundary intact and the response comes back.
+func TestIngestMail_Hook(t *testing.T) {
+	_, srv, cli, _ := newServerWithStore(t)
+	var got IngestMailReq
+	srv.IngestMailFn = func(_ context.Context, req IngestMailReq) (IngestMailResp, error) {
+		got = req
+		return IngestMailResp{TaskIDs: []int64{7}, Created: 1}, nil
+	}
+	resp, err := cli.IngestMail(context.Background(), IngestMailReq{
+		Mailbox: "INBOX", UID: 12, Subject: "Счёт", Body: "Оплатить.", Junk: false,
+	})
+	if err != nil {
+		t.Fatalf("IngestMail: %v", err)
+	}
+	if resp.Created != 1 || len(resp.TaskIDs) != 1 || resp.TaskIDs[0] != 7 {
+		t.Errorf("resp = %+v", resp)
+	}
+	if got.UID != 12 || got.Subject != "Счёт" || got.Body != "Оплатить." {
+		t.Errorf("req across the wire = %+v", got)
+	}
+}

internal/ipc/server.go

@@ -421,6 +421,17 @@ type Server struct {
 	// Set by the daemon; nil ⇒ MethodStoreEncryptionKey returns ErrUnknownMethod.
 	WrapKeyFn WrapKeyFunc
 
+	// IngestMailFn — extracts task candidates from one fetched message. Set by
+	// the daemon only when an email block is configured AND there is a
+	// llama-server to extract with; nil ⇒ MethodIngestMail returns
+	// ErrUnknownMethod, so a mail reader pointed at a core that is not
+	// configured for mail is refused rather than silently ignored.
+	//
+	// Like StepUp/WrapKeyFn/UnlockFn this bypasses CoreAPI: it is not a store
+	// operation, it needs the resident model, and it must not become a method
+	// every CoreAPI implementation has to carry.
+	IngestMailFn IngestMailFunc
+
 	// UnlockFn — unwraps the store encryption key from the wrapped blob using
 	// the passkey credential public key, opens the encrypted store, and wires
 	// the rest of the daemon (voice, loop, delivery). Set by the daemon when
@@ -439,6 +450,9 @@ type WrapKeyFunc func(ctx context.Context, publicKey []byte) error
 // public key and completes daemon initialization.
 type UnlockFunc func(ctx context.Context, publicKey []byte) error
 
+// IngestMailFunc — core-side mail extraction. Returns what was captured.
+type IngestMailFunc func(ctx context.Context, req IngestMailReq) (IngestMailResp, error)
+
 // CheckFunc — the auth hook signature. Wired by the daemon (auth.Gate.Check
 // satisfies this); dispatch calls it once per request after param-unmarshal
 // independence (it gets the raw params, may unmarshal what it needs — ipc
@@ -606,9 +620,10 @@ func withoutParams[R any](fn func(ctx context.Context, api CoreAPI) (R, error))
 // existed) as an argument — so SetAPI's runtime swap (the unlock transition)
 // is still honored on the very next request with no extra plumbing here.
 //
-// MethodAssertStepUp, MethodStoreEncryptionKey and MethodUnlock are NOT in
-// this table: they bypass CoreAPI entirely (s.StepUp / s.WrapKeyFn /
-// s.UnlockFn), so dispatch special-cases them before consulting the table.
+// MethodAssertStepUp, MethodStoreEncryptionKey, MethodUnlock and
+// MethodIngestMail are NOT in this table: they bypass CoreAPI entirely
+// (s.StepUp / s.WrapKeyFn / s.UnlockFn / s.IngestMailFn), so dispatch
+// special-cases them before consulting the table.
 var methodTable = map[Method]handlerFunc{
 	MethodWriteFact: withParams(func(ctx context.Context, api CoreAPI, p WriteFactReq) (idResp, error) {
 		id, err := api.WriteFact(ctx, p)
@@ -816,7 +831,7 @@ func (s *Server) dispatch(ctx context.Context, req Request) (json.RawMessage, er
 		}
 	}
 
-	// These three bypass CoreAPI entirely — they drive Server fields set
+	// These bypass CoreAPI entirely — they drive Server fields set
 	// directly by the daemon (StepUp / WrapKeyFn / UnlockFn), not store
 	// state, so they can never be table entries keyed on a CoreAPI method.
 	switch req.Method {
@@ -845,6 +860,20 @@ func (s *Server) dispatch(ctx context.Context, req Request) (json.RawMessage, er
 			return marshalResult(nil), s.UnlockFn(ctx, p.PublicKey)
 		}
 		return nil, fmt.Errorf("%w: %s", ErrUnknownMethod, req.Method)
+
+	case MethodIngestMail:
+		if s.IngestMailFn != nil {
+			var p IngestMailReq
+			if err := unmarshalParams(req.Params, &p); err != nil {
+				return nil, err
+			}
+			resp, err := s.IngestMailFn(ctx, p)
+			if err != nil {
+				return nil, err
+			}
+			return marshalResult(resp), nil
+		}
+		return nil, fmt.Errorf("%w: %s", ErrUnknownMethod, req.Method)
 	}
 
 	h, ok := methodTable[req.Method]

internal/ipc/wire.go

@@ -50,6 +50,7 @@ const (
 	MethodCaptureTask            Method = "capture_task"
 	MethodListTasks              Method = "list_tasks"
 	MethodSetTaskStatus          Method = "set_task_status"
+	MethodIngestMail             Method = "ingest_mail"
 )
 
 // Request — one frame from module to core. Params is the JSON-encoded argument