Let a queued message be taken back into the composer

TODO.md

@@ -2,9 +2,6 @@
 
 # M1 — One agent end to end
 
-- Cancel a queued message
-  A × on the transcript's "queued…" bubble withdraws the `task_inputs` row with a new `DELETE`, refused once the message has been handed over, and puts its text and images back in the composer. Claude Code, Zed and Devin all let a queued follow-up be taken back.
-
 # M2 — Seeing the work
 
 - Comment on diff lines in the Changes view

api/openapi.yaml

@@ -762,6 +762,20 @@ paths:
         "404": { $ref: "#/components/responses/Error" }
         "409": { $ref: "#/components/responses/Error" }
 
+  /api/tasks/{taskId}/queue/{inputId}:
+    parameters:
+      - { name: taskId, in: path, required: true, schema: { type: string } }
+      - { name: inputId, in: path, required: true, schema: { type: integer, format: int64 } }
+    delete:
+      operationId: withdrawMessage
+      description: >
+        Takes back a queued message (the id from its user.queued event) before the agent gets it, and records a
+        user.unqueued event. Refused once the message has been handed over.
+      responses:
+        "204": { description: The message was withdrawn. }
+        "404": { $ref: "#/components/responses/Error" }
+        "409": { $ref: "#/components/responses/Error" }
+
   /api/sessions/{sessionId}:
     parameters:
       - { name: sessionId, in: path, required: true, schema: { type: string } }

internal/agents/queue.go

@@ -75,7 +75,42 @@ func (m *Manager) Message(ctx context.Context, sessionID, actor, text, model str
 	return sess, nil
 }
 
+func (m *Manager) Withdraw(ctx context.Context, taskID string, inputID int64, actor string) error {
+	task, err := m.store.GetTask(ctx, taskID)
+	if err != nil {
+		return err
+	}
+	sessions, err := m.store.ListSessions(ctx, taskID)
+	if err != nil {
+		return err
+	}
+	if len(sessions) == 0 {
+		return fmt.Errorf("%w: message %d is not queued", ErrConflict, inputID)
+	}
+	sess := sessions[len(sessions)-1]
+
+	unlock := m.lockDelivery(queueLockKey(taskID))
+	defer unlock()
+
+	err = m.store.WithdrawTaskInput(ctx, taskID, inputID, task.ProjectId, sess.Id, actor)
+	if errors.Is(err, store.ErrNotFound) {
+		return fmt.Errorf("%w: message %d is not queued", ErrConflict, inputID)
+	}
+	if err != nil {
+		return err
+	}
+	slog.Info("queued message withdrawn", "session", sess.Id, "task", taskID, "input", inputID, "actor", actor)
+	return nil
+}
+
+func queueLockKey(taskID string) string {
+	return "task:" + taskID
+}
+
 func (m *Manager) deliverQueued(ctx context.Context, sess api.AgentSession) (bool, error) {
+	unlock := m.lockDelivery(queueLockKey(sess.TaskId))
+	defer unlock()
+
 	inputs, err := m.store.TaskInputs(ctx, sess.TaskId)
 	if err != nil || len(inputs) == 0 {
 		return false, err
@@ -131,6 +166,9 @@ func (m *Manager) takeQueuedMidTurn(ctx context.Context, l *live) []store.TaskIn
 		return nil
 	}
 
+	unlock := m.lockDelivery(queueLockKey(l.taskID))
+	defer unlock()
+
 	inputs, err := m.store.TaskInputs(ctx, l.taskID)
 	if err != nil {
 		slog.Error("list queued messages", "session", l.id, "err", err)

internal/api/api.gen.go

@@ -1624,6 +1624,9 @@ type ServerInterface interface {
 	// (GET /api/tasks/{taskId}/previews)
 	ListPreviews(w http.ResponseWriter, r *http.Request, taskId string)
 
+	// (DELETE /api/tasks/{taskId}/queue/{inputId})
+	WithdrawMessage(w http.ResponseWriter, r *http.Request, taskId string, inputId int64)
+
 	// (GET /api/tasks/{taskId}/reviews)
 	ListReviews(w http.ResponseWriter, r *http.Request, taskId string)
 
@@ -3008,6 +3011,41 @@ func (siw *ServerInterfaceWrapper) ListPreviews(w http.ResponseWriter, r *http.R
 	handler.ServeHTTP(w, r)
 }
 
+// WithdrawMessage operation middleware
+func (siw *ServerInterfaceWrapper) WithdrawMessage(w http.ResponseWriter, r *http.Request) {
+
+	var err error
+	_ = err
+
+	// ------------- Path parameter "taskId" -------------
+	var taskId string
+
+	err = runtime.BindStyledParameterWithOptions("simple", "taskId", r.PathValue("taskId"), &taskId, runtime.BindStyledParameterOptions{ParamLocation: runtime.ParamLocationPath, Explode: false, Required: true, Type: "string", Format: "", ValueIsUnescaped: true})
+	if err != nil {
+		siw.ErrorHandlerFunc(w, r, &InvalidParamFormatError{ParamName: "taskId", Err: err})
+		return
+	}
+
+	// ------------- Path parameter "inputId" -------------
+	var inputId int64
+
+	err = runtime.BindStyledParameterWithOptions("simple", "inputId", r.PathValue("inputId"), &inputId, runtime.BindStyledParameterOptions{ParamLocation: runtime.ParamLocationPath, Explode: false, Required: true, Type: "integer", Format: "int64", ValueIsUnescaped: true})
+	if err != nil {
+		siw.ErrorHandlerFunc(w, r, &InvalidParamFormatError{ParamName: "inputId", Err: err})
+		return
+	}
+
+	handler := http.Handler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		siw.Handler.WithdrawMessage(w, r, taskId, inputId)
+	}))
+
+	for _, middleware := range siw.HandlerMiddlewares {
+		handler = middleware(handler)
+	}
+
+	handler.ServeHTTP(w, r)
+}
+
 // ListReviews operation middleware
 func (siw *ServerInterfaceWrapper) ListReviews(w http.ResponseWriter, r *http.Request) {
 
@@ -3562,6 +3600,7 @@ func HandlerWithOptions(si ServerInterface, options StdHTTPServerOptions) http.H
 	m.HandleFunc(http.MethodPost+" "+options.BaseURL+"/api/tasks/{taskId}/snapshots/{n}/fork", wrapper.ForkSnapshot)
 	m.HandleFunc(http.MethodGet+" "+options.BaseURL+"/api/tasks/{taskId}/sessions", wrapper.ListSessions)
 	m.HandleFunc(http.MethodPost+" "+options.BaseURL+"/api/tasks/{taskId}/sessions", wrapper.CreateSession)
+	m.HandleFunc(http.MethodDelete+" "+options.BaseURL+"/api/tasks/{taskId}/queue/{inputId}", wrapper.WithdrawMessage)
 	m.HandleFunc(http.MethodGet+" "+options.BaseURL+"/api/sessions/{sessionId}", wrapper.GetSession)
 	m.HandleFunc(http.MethodPost+" "+options.BaseURL+"/api/sessions/{sessionId}/messages", wrapper.SendMessage)
 	m.HandleFunc(http.MethodPost+" "+options.BaseURL+"/api/sessions/{sessionId}/compact", wrapper.CompactSession)
@@ -3798,25 +3837,27 @@ var swaggerSpec = []string{
 	"S2+qNF9IM1MNDvMcBnj8iJdteBCvHcCEWwaD+fpVgVE8eHp5JwVz9CxRiZHaRrY6OpU5SlaZtgSMPiAs",
 	"NXoWPDtTL5RB7DELwT9VTZpJLjCadXngeyEmdJijO/iYIWsnOzt6ub7+3b3/GeblMI6vnEStOeRvq5Fl",
 	"bV0ooJv6sLY+sk70xyU0rTJ3BElsuKd88iBbSt34mUT8cDeqF+4DHwvTYkI/O0dJGZxDrQ+VsGBf/P7i",
-	"4u15NRSIOmHEusxeOJKm9G1c8dMk+OE4v30zi9Dcvn7Stw/aJFstNq2QpVsrl7lKD4uVbu7WuyfcrHf3",
+	"4u15NRSIOmHEusxeOJKm9G1c8dMk+OE4v30zi9Dcvn7Sh2IahEyv27CRknCwMHmtPJvYYohG9Dl8RgFp",
-	"2qt/mK0qZE/chPNXn8OwR3lGMjp+PVuxKyzK9BcyFjzBuXBrUrAtVUyy0wt4LMcrURhRHh/35SOWuPff",
+	"MeeHJ/dgboT2ocM8py3h3UJhWH/VCwFlz+LW5B93VCUxvXHkJeazVQbDsKDBTdlPMN7KeezHrhRfF9k4",
-	"J2HOPjdz5jrzj3EdR9K4F2FNjYfaxHjryqhBZtG+wysPCrasCv2tciqF51wrQLEgnJr7Y7iES7M8/mg+",
+	"n3elfSXavupjOd4cN39rT7uNnmMYtg9hSt4A2LRCoWGtXOaMPyyHu0kP3j0hOXh3L2rwD0MMCvk5N+H8",
-	"7XcRn7EH3m30zUnSnAxjl/R5gsNT0KM42r60KAH+H4D4x6nCfh1DqfBHE1aqYkfm/glJdmQGiilm2F+p",
+	"1WfJ7N1tIzlDv56t2BV4Z/oLGQvP4WzLNalwlyqmceqF1JYj4ihQLY/A/PIxcdz775OSaR/eL3PO+sdg",
-	"lLeMlAbJ8pyF/NCBqFJRRqpg1qPFKGMDgmnTKj/sgNrOrLlRzpMRiKKGfLA2pbzqB+bcKFNbxzFkcRjY",
+	"+CJp3IuwpsZDfXXk62S0UbDyqMMrDypc1YWH3SqnUgDYtQIUC8KpuT8GNq80y+OP5tN+rN4Z+3jeRu+v",
-	"i0PS/Gdk6iCn6rE8Zi8+IlXM0WGbkxsqx+tUIV7Ibk5RkZc0vLSm2L8MoqskUM7D9p111+ddbNP/yTS0",
+	"pC+QYYwNPE9weAp6FEfblxYlwP8DEP84VdivYyhG/2jicJkNMfdPebMj91RMYsQecaXMeKSWSr4NWVAZ",
-	"m7Bn+VofVV2wVzafck7VPPqnS66qlWf3JK/eg9cRFoNgHGmyUpTRnpHQioNHozrqTEjKz+qwuVqh1yvB",
+	"HYgqlf2kGnk9WoxaHEAwbVrlhx1Q25k1N8p5MjNSXJoP1qakav3Qrxtlaus4SjEOA3txSLaljEwd5FQ9",
-	"ZeowKtLems5ESXmQN2R+6a6znLaPxdlkIzx5ot+HZu8ZoFxQbqWNbLY4q/2irs7t7FoF9rYhY1yOB9xH",
+	"FmDtReCkmkw6bHOjRPNLXcXU60J2c4qq4mRDoDXF/mUQXa2Kcqa/76y7Pu+i5/5PLqvdhD3LCPyoCqm9",
-	"JaRo7EIb4ZeqaSiNc+7Lk7k1z2wDjhN04+s51YbMFDlI8jwVVCfKRizubcTOOChj5kyZ0NyJtdMGNcQh",
+	"8kWVs/bm8WVd+l6tPDvAefUe/Nqw3AjjSJMVO40Ws4RWHJ4cFZ5nQlIGYIfN1Qr9qgkuU4dxt/bWdEZw",
-	"ekzbNqxbZoaBsGPBO/Bn9dF3jkmapzGpGhmPpg1/O2jKCi9wxEPTIua0Ti+Xtqmp7MUFT/Jc/9aZ/BWD",
+	"lBg3tUrSXWdZkx+Ls8lGePJU0g/NDzVAuaDcShvZbHGH/EVdndvZtQrsz0Xm3hwPuI9KSNHYhTbCL1XT",
-	"R33Q0amA1smmSqS8M1sr8e3JyUkyaEJzQQXwk+e2kn6re1Ecfz8PI9iTraRkqwvpiF8qbPDDOx36MH1z",
+	"UKLw3Fssc5yf2QZcc+jG13OqPpqpCpHkeSrZT5SNWNzbiJ1xUMbMmTKhuRNrB7dEzT4JMLptw7plZhgI",
-	"8s0mip5jiaQOLTuEXTsb7Mw2f2xHvNYQw727GsdQtARM5hsBbc5j2uLaKm8OQjHy7uc4+mNmzI9jjGXN",
+	"O5ZUBI9pH70zmaR5GpPq3fFoKB4XmrLaAlw90XiNWdPTy6VtaiqscsGTPNe/dU4lisGjPujotkLrZGM4",
-	"5/fxtpn+N9vhmBZ3q0AYG3Uc4NzZ31JwCaqlZ8hA11UW5A6UdCp+kEE5oWrN2n6yT/lcaMS+a2sOAoN5",
+	"Ut6ZrZX49uTkJJnMoTlAMLQ+xQYo6bc6sMXx9/Nhgz3ZSkq2OimPeD7DBj+806GX3Dcn32yi6DkW4erQ",
-	"hC9k2vRLnPMjm5PSOGNOfAAEk1bw9UtrcabHrjXbNfLR62i4Sa41mW1HNdYsvAj2NGaQ0IZSTPYRpRMT",
+	"skPYtbPBzmzzx3b1bA0x3LvrvQxFS8BkvhHQq2HMHlFb5c1BKMZ2/hxHf8yaDHGMsboM/D7eNtP/Zjsc",
-	"0N0LFQEUlBRkUDG6xt3FrPwSGQa1WlOJ4qrzTePHnoUzuqKzsO3IJ4BsNoJBcVdjCc5HQqB8mDEVb2sO",
+	"Ey9vFQhjo44DnDv7WwpfQjXnDBnousrSKAAlnYofZFBOqFqzPYk0xT4XGrHv2pqDwGAe4QuZNv0S5/zI",
-	"fIL1V4g+cdu363Z/Sa2eQpkSR2MWeh+dCmaRSTh8QNGrTItSu86qlPO8CQLHH+HdHrWRxonTltpI4kKS",
+	"Bss0zpibKADBpBV8/dJanCnUit1u84l+bcNNcq3JrIeqsWbhRbCnMUeJNpTEtI8onZiADoWoCKCwtyCD",
-	"xVUGJq06YEEqzmAws+u7B+HHWGqih5HQOzl0nd7L2TmDPNh0T/Hoxxm87IiG9OI/nr/5gcpKm8xDn8ON",
+	"ivFb7i7WfZDIMKjVmopgV533Iz/2LJzRFZ0lBoh8AshmIxgUdzUWeX0kBMqHGVPxtubAJ1h/hegTt327",
-	"Y4qtRzop+N+XkIejLgmDCNaNnGWup3kKegIHyD7jwMA4zX8//+nHqMsB1NU++S8Bhf4G2NdvTk56/ksZ",
+	"bveX1OoplClxNGah99GpYJ6ihMMHFB/NtCi16+yWOc+bIHD8Ed7tUX1rnDhtqb4lgNzwdUmkVQcsecY5",
-	"RkXJmTCrN5MhjhVI5tu2jy37SMN7IcrTJcHdoBlby38O7vN7lff49Ol/DwA=",
+	"MmZ2ffcg/BhLfvUwEnonh875e7nTZ5AHr4FTPPpxBi87oiG9+I/nb37AK0SaLAaEA9pjErdHOin435eQ",
+	"h6MuCcNU1o2cZc7NeZEDAgfIPuPAwEjgfz//6ceoywHU1T55yAGF/kYEK745Oel5yGUYFSVnwqzeTIY4",
+	"ViCZb9s+tuwjDe+FKE+XZnmDZmwtMDu4z+9VQObTp/89AA==",
 }
 
 // decodeSpec returns the embedded OpenAPI spec as raw JSON bytes,

internal/server/server.go

@@ -779,6 +779,15 @@ func (s *Server) SendMessage(w http.ResponseWriter, r *http.Request, sessionID s
 	writeJSON(w, http.StatusAccepted, sess)
 }
 
+func (s *Server) WithdrawMessage(w http.ResponseWriter, r *http.Request, taskID string, inputID int64) {
+	err := s.agents.Withdraw(r.Context(), taskID, inputID, actor(r))
+	if err != nil {
+		writeAgentError(w, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
 func (s *Server) CompactSession(w http.ResponseWriter, r *http.Request, sessionID string) {
 	sess, err := s.agents.Compact(r.Context(), sessionID)
 	if err != nil {

internal/store/taskinputs.go

@@ -26,15 +26,36 @@ func (s *Store) AddTaskInput(ctx context.Context, in TaskInput, projectID, sessi
 		payload["images"] = in.Images
 	}
 	return s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
-		_, err := tx.ExecContext(ctx, `INSERT INTO task_inputs (task_id, actor, text, images, created_at) VALUES (?, ?, ?, ?, ?)`,
+		res, err := tx.ExecContext(ctx, `INSERT INTO task_inputs (task_id, actor, text, images, created_at) VALUES (?, ?, ?, ?, ?)`,
 			in.TaskID, in.Actor, in.Text, string(images), now())
 		if err != nil {
 			return err
 		}
+		payload["id"], err = res.LastInsertId()
+		if err != nil {
+			return err
+		}
 		return emit(sessionEvent("user.queued", projectID, in.TaskID, "", sessionID, in.Actor, payload))
 	})
 }
 
+func (s *Store) WithdrawTaskInput(ctx context.Context, taskID string, id int64, projectID, sessionID, actor string) error {
+	return s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
+		res, err := tx.ExecContext(ctx, `DELETE FROM task_inputs WHERE id = ? AND task_id = ?`, id, taskID)
+		if err != nil {
+			return err
+		}
+		n, err := res.RowsAffected()
+		if err != nil {
+			return err
+		}
+		if n == 0 {
+			return ErrNotFound
+		}
+		return emit(sessionEvent("user.unqueued", projectID, taskID, "", sessionID, actor, map[string]any{"id": id}))
+	})
+}
+
 func (s *Store) TaskInputs(ctx context.Context, taskID string) ([]TaskInput, error) {
 	rows, err := s.db.QueryContext(ctx, `SELECT id, task_id, actor, text, images, created_at FROM task_inputs WHERE task_id = ? ORDER BY id`, taskID)
 	if err != nil {

mac/Sources/Byre/Chat.swift

@@ -264,6 +264,29 @@ final class ChatModel {
         }
     }
 
+    func withdraw(_ p: PendingSend, _ overlays: Overlays) async {
+        guard let taskId, let inputId = p.inputId else {
+            return
+        }
+        let key = "message:\(taskId)"
+        do {
+            var imgs: [PendingImage] = []
+            for id in p.imageIds {
+                let data = try await ImageCache.fetch(.blob(id), store.api)
+                guard let image = NSImage(data: data) else {
+                    throw ApiError(status: 0, message: "not an image")
+                }
+                imgs.append(PendingImage(data: data, image: image))
+            }
+            _ = try await store.api.client.withdrawMessage(path: .init(taskId: taskId, inputId: Int64(inputId))).noContent
+            builder.withdrawn(inputId)
+            store.drafts?.restoreText(key, p.text)
+            store.images.restore(key, imgs)
+        } catch {
+            overlays.showAlert(errorText(error))
+        }
+    }
+
     func interrupt(_ sessionId: String, _ overlays: Overlays) {
         Task {
             do {
@@ -525,7 +548,7 @@ private struct TranscriptScroll: View {
                         RowView(row: row, model: model, nested: false)
                     }
                     ForEach(model.builder.pending) { p in
-                        PendingView(pending: p)
+                        PendingView(pending: p, model: model)
                     }
                 }
             }
@@ -647,13 +670,30 @@ private final class ScannerView: NSView {
 
 private struct PendingView: View {
     let pending: PendingSend
+    let model: ChatModel
+    @Environment(Overlays.self) private var overlays
+    @ViewState private var withdrawing = false
 
     var body: some View {
         TrailingBubble {
             VStack(alignment: .leading, spacing: 2) {
+                HStack(spacing: 8) {
                     Text(pending.queued ? "queued…" : "sending…")
                         .font(Fonts.font(11, italic: true))
                         .foregroundStyle(Palette.muted)
+                    if pending.inputId != nil {
+                        Button("×") {
+                            withdrawing = true
+                            Task {
+                                await model.withdraw(pending, overlays)
+                                withdrawing = false
+                            }
+                        }
+                        .buttonStyle(ThumbRemoveStyle())
+                        .disabled(withdrawing)
+                        .help("Take this message back into the composer")
+                    }
+                }
                 if !pending.images.isEmpty {
                     FlowLayout(spacing: 6) {
                         ForEach(pending.images) { img in

mac/Sources/Byre/Composer.swift

@@ -237,7 +237,7 @@ struct Thumbnails: View {
     }
 }
 
-private struct ThumbRemoveStyle: ButtonStyle {
+struct ThumbRemoveStyle: ButtonStyle {
     func makeBody(configuration: ButtonStyleConfiguration) -> some View {
         ThumbRemove(configuration: configuration)
     }
@@ -371,6 +371,11 @@ struct ComposerView: View {
             store.drafts?.setComposerImages(draftKey, store.images.images(draftKey).count)
             reportDraft()
         }
+        .onChange(of: store.drafts?.composerText(draftKey)) { _, new in
+            if let new, new != text {
+                text = new
+            }
+        }
         .onChange(of: store.images.images(draftKey).count) {
             store.drafts?.setComposerImages(draftKey, store.images.images(draftKey).count)
         }

mac/Sources/Byre/Drafts.swift

@@ -192,15 +192,20 @@ final class Drafts {
         if ok {
             lostImages[send.key] = nil
         } else {
-            let text = [send.text, composerTexts[send.key] ?? ""].filter { !$0.isEmpty }.joined(separator: "\n\n")
+            restoreText(send.key, send.text)
-            if !text.isEmpty {
-                composerTexts[send.key] = text
-            }
         }
         dirty = true
         flush()
     }
 
+    func restoreText(_ key: String, _ text: String) {
+        let joined = [text, composerTexts[key] ?? ""].filter { !$0.isEmpty }.joined(separator: "\n\n")
+        if !joined.isEmpty {
+            composerTexts[key] = joined
+        }
+        save()
+    }
+
     func checkedAnswer(_ id: String) -> [String] {
         checked[id] ?? []
     }

mac/Sources/Byre/Images.swift

@@ -67,7 +67,7 @@ final class ImageCache {
         return img
     }
 
-    private static func fetch(_ source: ImageSource, _ api: API) async throws -> Data {
+    static func fetch(_ source: ImageSource, _ api: API) async throws -> Data {
         switch source {
         case .data(let data):
             return data

mac/Sources/Byre/TranscriptBuilder.swift

@@ -135,6 +135,7 @@ struct PendingSend: Identifiable {
     let local: Bool
     let queued: Bool
     let md: [MDBlock]
+    var inputId: Int? = nil
 }
 
 @MainActor
@@ -231,6 +232,10 @@ final class TranscriptBuilder {
         }
     }
 
+    func withdrawn(_ inputId: Int) {
+        pending.removeAll { $0.inputId == inputId }
+    }
+
     private func confirmPending(_ text: String, queued: Bool, local: Bool) {
         let i = queued ? pending.firstIndex { !$0.local && $0.text == text } : nil
         if let i = i ?? (local ? pending.firstIndex { $0.local && $0.text == text } : nil) {
@@ -417,7 +422,13 @@ final class TranscriptBuilder {
                     confirmPending(text, queued: false, local: true)
                     pendingIds += 1
                     let images = (p["images"] as? [(any Sendable)?] ?? []).map { jsString($0) }
-                    pending.append(PendingSend(id: pendingIds, text: text, images: [], imageIds: images, local: false, queued: true, md: trimmed(text).isEmpty ? [] : parseMarkdown(text)))
+                    pending.append(PendingSend(id: pendingIds, text: text, images: [], imageIds: images, local: false, queued: true, md: trimmed(text).isEmpty ? [] : parseMarkdown(text), inputId: int(p, "id")))
+                }
+                continue
+            }
+            if ev.kind == "user.unqueued" {
+                if sink == nil, let id = int(p, "id") {
+                    withdrawn(id)
                 }
                 continue
             }