diff --git a/src/resources/extensions/gsd/tests/workflow-logger-audit.test.ts b/src/resources/extensions/gsd/tests/workflow-logger-audit.test.ts
new file mode 100644
index 000000000..1859bf1d8
--- /dev/null
+++ b/src/resources/extensions/gsd/tests/workflow-logger-audit.test.ts
@@ -0,0 +1,120 @@
+// GSD Extension — Workflow Logger Audit Persistence Tests
+// Validates error-only persistence, sanitization, and warning ephemeral behavior.
+
+import { describe, test, beforeEach, afterEach } from "node:test";
+import assert from "node:assert/strict";
+import { mkdtempSync, mkdirSync, readFileSync, existsSync, rmSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+
+import {
+  logWarning,
+  logError,
+  setLogBasePath,
+  _resetLogs,
+  peekLogs,
+  drainLogs,
+} from "../workflow-logger.ts";
+
+function createTempProject(): string {
+  const tmp = mkdtempSync(join(tmpdir(), "gsd-wflog-test-"));
+  mkdirSync(join(tmp, ".gsd"), { recursive: true });
+  return tmp;
+}
+
+function readAuditLines(basePath: string): Record<string, unknown>[] {
+  const auditPath = join(basePath, ".gsd", "audit-log.jsonl");
+  if (!existsSync(auditPath)) return [];
+  const content = readFileSync(auditPath, "utf-8").trim();
+  if (!content) return [];
+  return content.split("\n").map((line) => JSON.parse(line));
+}
+
+describe("workflow-logger audit persistence", () => {
+  let tmp: string;
+
+  beforeEach(() => {
+    tmp = createTempProject();
+    _resetLogs();
+    setLogBasePath(tmp);
+  });
+
+  afterEach(() => {
+    _resetLogs();
+    setLogBasePath(null as unknown as string);
+    rmSync(tmp, { recursive: true, force: true });
+  });
+
+  test("logError persists to audit-log.jsonl", () => {
+    logError("engine", "something broke");
+    const lines = readAuditLines(tmp);
+    assert.equal(lines.length, 1);
+    assert.equal(lines[0].severity, "error");
+    assert.equal(lines[0].component, "engine");
+  });
+
+  test("logWarning does NOT persist to audit-log.jsonl", () => {
+    logWarning("engine", "something fishy");
+    const lines = readAuditLines(tmp);
+    assert.equal(lines.length, 0, "warnings must not be persisted to audit log");
+  });
+
+  test("logWarning still appears in in-memory buffer", () => {
+    logWarning("recovery", "probe miss");
+    const entries = peekLogs();
+    assert.equal(entries.length, 1);
+    assert.equal(entries[0].severity, "warn");
+    assert.equal(entries[0].component, "recovery");
+  });
+
+  test("persisted error messages are truncated at 200 chars", () => {
+    const longMessage = "x".repeat(300);
+    logError("engine", longMessage);
+    const lines = readAuditLines(tmp);
+    assert.equal(lines.length, 1);
+    const msg = lines[0].message as string;
+    assert.ok(msg.length <= 215, `message should be truncated, got ${msg.length} chars`);
+    assert.ok(msg.endsWith("…[truncated]"));
+  });
+
+  test("persisted errors have context filtered to safe allowlist", () => {
+    logError("tool", "tool failed", {
+      fn: "saveDecisionToDb",
+      tool: "gsd_decision_save",
+      error: "SQLITE_BUSY: database is locked",
+      file: "/home/user/project/gsd.db",
+    });
+    const lines = readAuditLines(tmp);
+    assert.equal(lines.length, 1);
+    const ctx = lines[0].context as Record<string, string>;
+    assert.ok(ctx, "context should exist");
+    assert.equal(ctx.fn, "saveDecisionToDb");
+    assert.equal(ctx.tool, "gsd_decision_save");
+    assert.equal(ctx.error, undefined, "error key must be stripped from persisted context");
+    assert.equal(ctx.file, undefined, "file key must be stripped from persisted context");
+  });
+
+  test("persisted errors omit context when no safe keys present", () => {
+    logError("bootstrap", "ensureDbOpen failed", {
+      error: "ENOENT",
+      cwd: "/home/user/project",
+    });
+    const lines = readAuditLines(tmp);
+    assert.equal(lines.length, 1);
+    assert.equal(lines[0].context, undefined, "context should be omitted when no safe keys match");
+  });
+
+  test("mixed warnings and errors only persist errors", () => {
+    logWarning("recovery", "main not found");
+    logWarning("recovery", "master not found");
+    logError("engine", "fatal failure");
+    logWarning("prompt", "cache miss");
+
+    const lines = readAuditLines(tmp);
+    assert.equal(lines.length, 1, "only the error should be persisted");
+    assert.equal(lines[0].severity, "error");
+
+    const buffered = drainLogs();
+    assert.equal(buffered.length, 4, "all entries should be in the in-memory buffer");
+  });
+});