diff --git a/workspace-server/internal/handlers/delegation.go b/workspace-server/internal/handlers/delegation.go
index 1bda2c63..0156f864 100644
--- a/workspace-server/internal/handlers/delegation.go
+++ b/workspace-server/internal/handlers/delegation.go
@@ -342,6 +342,18 @@ func (h *DelegationHandler) executeDelegation(sourceID, targetID, delegationID s
 		}
 	}
 
+	// When proxyA2ARequest returns an error but we have a non-empty response body
+	// with a 2xx status code, the agent completed the work successfully — the error
+	// is a delivery/transport error (e.g., connection reset after response was
+	// received). Treat as success: the response body is valid and the work is done.
+	// This prevents "retry storms" where the canvas sees error + Restart-workspace
+	// suggestion even though the delegation actually completed.
+	if proxyErr != nil && len(respBody) > 0 && status >= 200 && status < 300 {
+		log.Printf("Delegation %s: completed with delivery error (status=%d, respBody=%d bytes, proxyErr=%v) — treating as success",
+			delegationID, status, len(respBody), proxyErr.Error())
+		goto handleSuccess
+	}
+
 	if proxyErr != nil {
 		log.Printf("Delegation %s: failed — %s", delegationID, proxyErr.Error())
 		h.updateDelegationStatus(sourceID, delegationID, "failed", proxyErr.Error())
@@ -361,6 +373,8 @@ func (h *DelegationHandler) executeDelegation(sourceID, targetID, delegationID s
 		return
 	}
 
+handleSuccess:
+
 	// 202 + {queued: true} means the target was busy and the proxy
 	// enqueued the request for the next drain tick — NOT a completion.
 	// Treat it as such: write a clean 'queued' activity row with no
diff --git a/workspace-server/internal/handlers/template_import.go b/workspace-server/internal/handlers/template_import.go
index 7b16c17f..9dc5f078 100644
--- a/workspace-server/internal/handlers/template_import.go
+++ b/workspace-server/internal/handlers/template_import.go
@@ -267,22 +267,16 @@ func (h *TemplatesHandler) ReplaceFiles(c *gin.Context) {
 		return
 	}
 
-	// Container offline — try ephemeral container to write to volume
+	// Container offline — write to the config volume via ephemeral container.
+	// Do NOT fall back to the host-side template dir: the restart handler
+	// reads from the volume, not the template dir, so a template-dir write
+	// would silently succeed (200) while the file change is invisible to
+	// restarted containers (#151). Surface the error so the caller retries
+	// when Docker is available instead of believing the change persisted.
 	volName := provisioner.ConfigVolumeName(workspaceID)
 	if err := h.writeViaEphemeral(ctx, volName, body.Files); err != nil {
-		// Last resort: write to host-side template dir
-		destDir := h.resolveTemplateDir(wsName)
-		if destDir == "" {
-			log.Printf("ReplaceFiles: writeViaEphemeral failed and no template dir for %s: %v", workspaceID, err)
-			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to write files to workspace"})
-			return
-		}
-		os.MkdirAll(destDir, 0o755)
-		if err := writeFiles(destDir, body.Files); err != nil {
-			c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body"})
-			return
-		}
-		c.JSON(http.StatusOK, gin.H{"status": "replaced", "workspace": workspaceID, "files": len(body.Files), "source": "template"})
+		log.Printf("ReplaceFiles: writeViaEphemeral failed for %s (workspace %s offline): %v", wsName, workspaceID, err)
+		c.JSON(http.StatusServiceUnavailable, gin.H{"error": "workspace offline — retry after it starts"})
 		return
 	}
 
diff --git a/workspace-server/internal/handlers/template_import_test.go b/workspace-server/internal/handlers/template_import_test.go
index c496f9c5..59e3550d 100644
--- a/workspace-server/internal/handlers/template_import_test.go
+++ b/workspace-server/internal/handlers/template_import_test.go
@@ -452,3 +452,43 @@ func TestReplaceFiles_PathTraversal(t *testing.T) {
 		t.Errorf("unmet sqlmock expectations: %v", err)
 	}
 }
+
+// TestReplaceFiles_OfflineDocker_Returns503 ensures that when the workspace
+// container is offline AND the ephemeral Docker write fails (docker unavailable),
+// ReplaceFiles returns 503 instead of silently falling back to the template
+// directory. A template-dir write would be invisible after restart because
+// the restart handler reads from the Docker volume, not the template dir (#151).
+func TestReplaceFiles_OfflineDocker_Returns503(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	// nil docker → TemplatesHandler.docker == nil → findContainer returns "" (offline)
+	// → writeViaEphemeral returns error (docker not available) → handler should
+	// return 503, NOT fall back to the host-side template dir.
+	handler := NewTemplatesHandler(t.TempDir(), nil, nil)
+
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
+		WithArgs("ws-offline").
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).AddRow("Offline Agent", "", ""))
+
+	body := `{"files": {"initial-prompt.md": "updated prompt"}}`
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: "ws-offline"}}
+	c.Request = httptest.NewRequest("PUT", "/workspaces/ws-offline/files", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	handler.ReplaceFiles(c)
+
+	if w.Code != http.StatusServiceUnavailable {
+		t.Errorf("expected 503, got %d: %s", w.Code, w.Body.String())
+	}
+
+	if !strings.Contains(w.Body.String(), "offline") {
+		t.Errorf("response should mention 'offline': %s", w.Body.String())
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}