diff --git a/internal/executor/executor.go b/internal/executor/executor.go
index 002612bc..a6784be8 100644
--- a/internal/executor/executor.go
+++ b/internal/executor/executor.go
@@ -1933,7 +1933,18 @@ func (e *Executor) executeTask(ctx context.Context, task *db.Task) {
 
 	// Update final status and trigger hooks
 	// Respect status set by hooks - don't override blocked with done
-	if result.Interrupted {
+	if result.Requeued {
+		// The task was deliberately re-queued while its session was parked (e.g. a
+		// human moved a blocked task back to In Progress). Preserve the queued
+		// status the requeue set — do NOT write backlog — kill the stale session so
+		// the fresh run starts clean, and let the worker pick it up. Releasing the
+		// running-task slot happens in this goroutine's defer, which the worker's
+		// admission gate waits on, so the handoff is sequential (no double-session).
+		e.logLine(task.ID, "system", "Re-queued by user — starting a fresh run")
+		taskExecutor.Kill(task.ID)
+		e.TriggerProcessing() // wake the worker immediately instead of waiting for the next tick
+		return
+	} else if result.Interrupted {
 		// Explicitly set to backlog - don't assume Interrupt() already did it,
 		// as the interruption may have come from pollTmuxSession detecting a
 		// stale status or context cancellation.
@@ -2415,6 +2426,7 @@ type execResult struct {
 	NeedsInput  bool
 	Interrupted bool
 	Message     string
+	Requeued    bool
 }
 
 // TmuxDaemonSession is the default session name that holds all Claude task windows.
@@ -4094,9 +4106,14 @@ func (e *Executor) pollTmuxSession(ctx context.Context, taskID int64, sessionNam
 					return execResult{Success: true}
 				}
 				if task.Status == db.StatusQueued {
-					// Task was re-queued (e.g. retry) - stop polling so the
-					// worker can pick it up fresh without a duplicate session
-					return execResult{Interrupted: true}
+					// Task was re-queued (e.g. retry, or a human moving a blocked
+					// task back to In Progress) - stop polling so the worker can
+					// pick it up fresh without a duplicate session. Report this as
+					// Requeued, NOT Interrupted: a requeue is not a cancellation, and
+					// the finalizer must preserve the queued status rather than
+					// clobber it with backlog. (The only reader of Interrupted is the
+					// finalizer's else-if, which the Requeued branch short-circuits.)
+					return execResult{Requeued: true}
 				}
 			}
 
diff --git a/internal/executor/poll_tmux_requeue_test.go b/internal/executor/poll_tmux_requeue_test.go
new file mode 100644
index 00000000..c0b2519c
--- /dev/null
+++ b/internal/executor/poll_tmux_requeue_test.go
@@ -0,0 +1,100 @@
+package executor
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/bborn/workflow/internal/db"
+)
+
+// TestPollTmuxSessionRequeueVsBacklog covers the fix for issue #674: a parked
+// pollTmuxSession must distinguish a deliberate re-queue (a human moving a
+// blocked task back to "In Progress", which sets the task to queued) from a
+// genuine interrupt/cancel (task set to backlog).
+//
+//   - queued  -> {Interrupted: true, Requeued: true}  so executeTask's
+//     finalization PRESERVES the queued status instead of clobbering it with
+//     backlog, and lets the worker spawn a fresh run.
+//   - backlog -> {Interrupted: true}                  a genuine interrupt; the
+//     finalization writes backlog as before.
+//
+// Both statuses are checked at the very top of pollTmuxSession's tick, before
+// any tmux window probe, so a non-existent session name is fine here — the
+// function returns from the DB-status branch on the first tick (~1s).
+//
+// Note: the executeTask finalization branch itself (which turns a Requeued
+// result into "preserve queued + kill session + TriggerProcessing") is not
+// unit-tested here because executeTask spawns a real executor backend, sets up
+// git worktrees, and runs a live tmux session — none of which can be stubbed
+// with the current test helpers. The poll-level contract asserted below is the
+// signal that branch keys off of, so verifying it deterministically guards the
+// behavior that was broken.
+func TestPollTmuxSessionRequeueVsBacklog(t *testing.T) {
+	tests := []struct {
+		name            string
+		status          string
+		wantRequeued    bool
+		wantInterrupted bool
+	}{
+		{
+			// A requeue is NOT a cancellation: Requeued only, never Interrupted, so
+			// the finalizer preserves 'queued' instead of writing backlog.
+			name:            "re-queued task signals Requeued (not Interrupted)",
+			status:          db.StatusQueued,
+			wantRequeued:    true,
+			wantInterrupted: false,
+		},
+		{
+			name:            "backlog task is a genuine interrupt without Requeued",
+			status:          db.StatusBacklog,
+			wantRequeued:    false,
+			wantInterrupted: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			exec, database := newTestExecutor(t)
+
+			task := &db.Task{Title: "poll requeue test", Type: "task", Project: "test"}
+			if err := database.CreateTask(task); err != nil {
+				t.Fatal(err)
+			}
+			if err := database.UpdateTaskStatus(task.ID, tt.status); err != nil {
+				t.Fatal(err)
+			}
+
+			// Bound the test so a logic regression that fails to return can't hang
+			// the suite. pollTmuxSession returns from the DB-status branch on the
+			// first 1s tick; give it generous headroom.
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			defer cancel()
+
+			done := make(chan execResult, 1)
+			go func() {
+				done <- exec.pollTmuxSession(ctx, task.ID, "nonexistent-session-674")
+			}()
+
+			var result execResult
+			select {
+			case result = <-done:
+			case <-ctx.Done():
+				t.Fatalf("pollTmuxSession did not return for status %q within timeout", tt.status)
+			}
+
+			if result.Requeued != tt.wantRequeued {
+				t.Errorf("status %q: Requeued = %v, want %v", tt.status, result.Requeued, tt.wantRequeued)
+			}
+			if result.Interrupted != tt.wantInterrupted {
+				t.Errorf("status %q: Interrupted = %v, want %v", tt.status, result.Interrupted, tt.wantInterrupted)
+			}
+			// The two signals are mutually exclusive: a requeue must never also be
+			// flagged as an interrupt, or the finalizer's else-if could finalize it
+			// to backlog and undo the requeue.
+			if result.Requeued && result.Interrupted {
+				t.Errorf("status %q: both Requeued and Interrupted set", tt.status)
+			}
+		})
+	}
+}
diff --git a/internal/executor/task_executor.go b/internal/executor/task_executor.go
index 2a6a5122..de9a1902 100644
--- a/internal/executor/task_executor.go
+++ b/internal/executor/task_executor.go
@@ -13,6 +13,7 @@ type ExecResult struct {
 	NeedsInput  bool   // Task is waiting for user input
 	Interrupted bool   // Task was interrupted by user
 	Message     string // Status message or error
+	Requeued    bool   // Task was deliberately re-queued while running; caller must preserve queued, not write backlog
 }
 
 // toInternal converts ExecResult to the internal execResult type.