fix(hooks): gate empty-stdin diagnostics behind CLAUDE_MEM_STRICT_STDIN

Default empty stdin on non-lifecycle hooks is a no-op (Cursor fires these routinely). Set CLAUDE_MEM_STRICT_STDIN=1 to restore issue #2188 CAPTURE_BROKEN diagnostics for WSL/bash debugging.

Author: Steaeavean

plugin/scripts/bun-runner.js

@@ -161,59 +161,45 @@ if (child.stdin) {
       // Lifecycle commands don't need stdin — close pipe and let child run.
       try { child.stdin.end(); } catch {}
     } else {
-      // Issue #2188: empty/missing stdin previously masked by `|| '{}'` fallback,
-      // which silently hid WSL bash failures (e.g. hooks invoked under a broken
-      // shell that never piped a payload). Surface the failure mode instead.
-      const dataDir = process.env.CLAUDE_MEM_DATA_DIR || join(homedir(), '.claude-mem');
-      const payloadType = stdinData === null
-        ? 'null (no data event or stream error)'
-        : stdinData === undefined
-          ? 'undefined'
-          : Buffer.isBuffer(stdinData) && stdinData.length === 0
-            ? 'empty Buffer (zero bytes received)'
-            : `unexpected (${typeof stdinData})`;
-      const payloadByteLength = (stdinData && typeof stdinData.length === 'number')
-        ? stdinData.length
-        : 0;
-      const diagnostic = [
-        `[bun-runner] empty stdin payload received — issue #2188`,
-        `  script: ${args[0]}`,
-        `  payload byte length: ${payloadByteLength}`,
-        `  payload type: ${payloadType}`,
-        `  platform: ${process.platform}`,
-        `  shell: ${process.env.SHELL || 'n/a'}`,
-        `  stdin TTY: ${process.stdin.isTTY === true ? 'true' : process.stdin.isTTY === false ? 'false' : 'undefined'}`,
-        `  timestamp: ${new Date().toISOString()}`,
-        `  CLAUDE_PLUGIN_ROOT: ${RESOLVED_PLUGIN_ROOT}`,
-      ].join('\n');
-
-      // IO discipline (see src/shared/hook-io.ts intent vocabulary):
-      // - this stderr write is a USER_HINT (Claude Code surfaces it inline).
-      // - the CAPTURE_BROKEN marker file below is a DIAGNOSTIC durable signal for
-      //   the next session-start hint.
-      // - exit 0 below is the EXIT_SIGNAL per CLAUDE.md (Windows Terminal tab
-      //   management); the marker file, not the exit code, is the durable failure
-      //   signal. bun-runner runs in its own node process BEFORE hookCommand's
-      //   stderr buffer is installed, so this write is never swallowed.
-
-      // Write to stderr so Claude Code surfaces the diagnostic.
-      console.error(diagnostic);
-
-      // Persist diagnostic to the runner-errors log and drop a CAPTURE_BROKEN marker
-      // file so the next session-start hint can surface the failure. We exit 0 to
-      // honor the project's exit-code strategy (worker/hook errors exit 0 to
-      // prevent Windows Terminal tab pileup) — the marker file is the durable
-      // signal that something is wrong, not the exit code.
-      try {
-        const logsDir = join(dataDir, 'logs');
-        mkdirSync(logsDir, { recursive: true });
-        appendFileSync(join(logsDir, 'runner-errors.log'), diagnostic + '\n\n');
-        mkdirSync(dataDir, { recursive: true });
-        writeFileSync(join(dataDir, 'CAPTURE_BROKEN'), diagnostic + '\n');
-      } catch (writeErr) {
-        console.error(`[bun-runner] failed to persist diagnostic: ${writeErr && writeErr.message ? writeErr.message : writeErr}`);
+      // Non-lifecycle hooks with empty stdin are a no-op. Cursor (and the Claude
+      // Code ↔ Cursor bridge) routinely invoke shell/MCP hooks without a payload;
+      // issue #2188 diagnostics (CAPTURE_BROKEN + runner-errors.log) produced
+      // persistent false positives on macOS. Set CLAUDE_MEM_STRICT_STDIN=1 to
+      // restore the #2188 failure surface for WSL/bash debugging.
+      if (process.env.CLAUDE_MEM_STRICT_STDIN === '1') {
+        const dataDir = process.env.CLAUDE_MEM_DATA_DIR || join(homedir(), '.claude-mem');
+        const payloadType = stdinData === null
+          ? 'null (no data event or stream error)'
+          : stdinData === undefined
+            ? 'undefined'
+            : Buffer.isBuffer(stdinData) && stdinData.length === 0
+              ? 'empty Buffer (zero bytes received)'
+              : `unexpected (${typeof stdinData})`;
+        const payloadByteLength = (stdinData && typeof stdinData.length === 'number')
+          ? stdinData.length
+          : 0;
+        const diagnostic = [
+          `[bun-runner] empty stdin payload received — issue #2188`,
+          `  script: ${args[0]}`,
+          `  payload byte length: ${payloadByteLength}`,
+          `  payload type: ${payloadType}`,
+          `  platform: ${process.platform}`,
+          `  shell: ${process.env.SHELL || 'n/a'}`,
+          `  stdin TTY: ${process.stdin.isTTY === true ? 'true' : process.stdin.isTTY === false ? 'false' : 'undefined'}`,
+          `  timestamp: ${new Date().toISOString()}`,
+          `  CLAUDE_PLUGIN_ROOT: ${RESOLVED_PLUGIN_ROOT}`,
+        ].join('\n');
+        console.error(diagnostic);
+        try {
+          const logsDir = join(dataDir, 'logs');
+          mkdirSync(logsDir, { recursive: true });
+          appendFileSync(join(logsDir, 'runner-errors.log'), diagnostic + '\n\n');
+          mkdirSync(dataDir, { recursive: true });
+          writeFileSync(join(dataDir, 'CAPTURE_BROKEN'), diagnostic + '\n');
+        } catch (writeErr) {
+          console.error(`[bun-runner] failed to persist diagnostic: ${writeErr && writeErr.message ? writeErr.message : writeErr}`);
+        }
       }
-
       try { child.stdin.end(); } catch {}
       try { child.kill(); } catch {}
       process.exit(0);