fix: honor clipboard tool exit status

src/screens/repl.ts

@@ -69,6 +69,7 @@ import { MCPManager, loadMCPConfig, type MCPServerConfig } from "../mcp/client.j
 import { seedSystemMessages, MODE_PROMPTS } from "../agent/system-prompt.js";
 import { checkForUpdate } from "../utils/update.js";
 import { readClipboardImage, MAX_IMAGE_BYTES } from "../utils/clipboard-image.js";
+import { copyToClipboard } from "../utils/clipboard.js";
 import { SessionLedger } from "../agent/session-ledger.js";
 import { COMPACTION_PROMPT, extractSummary, MAX_CONSECUTIVE_COMPACT_FAILURES } from "../agent/compaction-prompt.js";
 import { compactMessagesForApi } from "../agent/compaction.js";
@@ -961,21 +962,6 @@ export async function runREPL(
 
   // ─── Clipboard helpers ────────────────────────────────────────────────────
 
-  /** Write text to the system clipboard cross-platform. Returns true on success. */
-  function copyToClipboard(text: string): boolean {
-    try {
-      if (process.platform === "darwin") {
-        spawnSync("pbcopy", [], { input: text, encoding: "utf-8" });
-      } else if (process.platform === "win32") {
-        spawnSync("clip", [], { input: text, encoding: "utf-8", shell: true });
-      } else {
-        const r = spawnSync("xclip", ["-selection", "clipboard"], { input: text, encoding: "utf-8" });
-        if (r.error) spawnSync("xsel", ["--clipboard", "--input"], { input: text, encoding: "utf-8" });
-      }
-      return true;
-    } catch { return false; }
-  }
-
   /** Convert StyledLine[] to plain text (strip all styling). */
   function styledLinesToText(lines: StyledLine[]): string {
     return lines.map(line => line.map(s => s.text).join("")).join("\n");

src/utils/clipboard.test.ts

@@ -0,0 +1,54 @@
+import { describe, expect, test } from "bun:test";
+import { copyToClipboard, type SpawnSyncFn } from "./clipboard";
+
+function fakeSpawn(
+  plan: Record<string, { status?: number | null; error?: Error }>,
+): SpawnSyncFn {
+  return (command) => {
+    const r = plan[command] ?? { status: 1, error: new Error("ENOENT") };
+    return {
+      status: r.status ?? null,
+      error: r.error,
+      signal: null,
+      output: [null, "", ""],
+      pid: 0,
+      stdout: "",
+      stderr: "",
+    };
+  };
+}
+
+describe("copyToClipboard", () => {
+  const original = process.platform;
+
+  test("darwin: succeeds only when pbcopy exits 0", () => {
+    Object.defineProperty(process, "platform", { value: "darwin" });
+    expect(copyToClipboard("hi", fakeSpawn({ pbcopy: { status: 0 } }))).toBe(true);
+    expect(copyToClipboard("hi", fakeSpawn({ pbcopy: { status: 1 } }))).toBe(false);
+    expect(copyToClipboard("hi", fakeSpawn({ pbcopy: { error: new Error("ENOENT") } }))).toBe(false);
+    Object.defineProperty(process, "platform", { value: original });
+  });
+
+  test("win32: succeeds only when clip exits 0", () => {
+    Object.defineProperty(process, "platform", { value: "win32" });
+    expect(copyToClipboard("hi", fakeSpawn({ clip: { status: 0 } }))).toBe(true);
+    expect(copyToClipboard("hi", fakeSpawn({ clip: { status: 1 } }))).toBe(false);
+    Object.defineProperty(process, "platform", { value: original });
+  });
+
+  test("linux: falls back from xclip to xsel; false when both fail", () => {
+    Object.defineProperty(process, "platform", { value: "linux" });
+    expect(copyToClipboard("hi", fakeSpawn({
+      xclip: { status: 0 },
+    }))).toBe(true);
+    expect(copyToClipboard("hi", fakeSpawn({
+      xclip: { error: new Error("ENOENT") },
+      xsel: { status: 0 },
+    }))).toBe(true);
+    expect(copyToClipboard("hi", fakeSpawn({
+      xclip: { error: new Error("ENOENT") },
+      xsel: { error: new Error("ENOENT") },
+    }))).toBe(false);
+    Object.defineProperty(process, "platform", { value: original });
+  });
+});

src/utils/clipboard.ts

@@ -0,0 +1,43 @@
+/**
+ * Cross-platform clipboard write.
+ *
+ * Returns true only when the platform clipboard tool exits successfully —
+ * missing binaries / non-zero status must not be reported as success.
+ */
+
+import { spawnSync, type SpawnSyncReturns } from "node:child_process";
+
+export type SpawnSyncFn = (
+  command: string,
+  args: string[],
+  options: { input: string; encoding: "utf-8"; shell?: boolean },
+) => SpawnSyncReturns<string>;
+
+function ok(r: SpawnSyncReturns<string>): boolean {
+  return !r.error && (r.status ?? 1) === 0;
+}
+
+/**
+ * Write `text` to the system clipboard.
+ * @param spawn injectable for unit tests (defaults to `spawnSync`)
+ */
+export function copyToClipboard(
+  text: string,
+  spawn: SpawnSyncFn = spawnSync as SpawnSyncFn,
+): boolean {
+  try {
+    if (process.platform === "darwin") {
+      return ok(spawn("pbcopy", [], { input: text, encoding: "utf-8" }));
+    }
+    if (process.platform === "win32") {
+      return ok(spawn("clip", [], { input: text, encoding: "utf-8", shell: true }));
+    }
+    // Linux / BSD — try xclip, then xsel
+    const xclip = spawn("xclip", ["-selection", "clipboard"], { input: text, encoding: "utf-8" });
+    if (ok(xclip)) return true;
+    const xsel = spawn("xsel", ["--clipboard", "--input"], { input: text, encoding: "utf-8" });
+    return ok(xsel);
+  } catch {
+    return false;
+  }
+}