diff --git a/tests/lib/session-parser.test.ts b/tests/lib/session-parser.test.ts
new file mode 100644
index 0000000..a217b42
--- /dev/null
+++ b/tests/lib/session-parser.test.ts
@@ -0,0 +1,277 @@
+/**
+ * Tests for session-parser.ts — JSONL session parsing, event extraction,
+ * correction detection, and timestamp normalization.
+ */
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { writeFileSync, mkdirSync, rmSync } from "fs";
+import { join } from "path";
+import { tmpdir } from "os";
+import { randomUUID } from "crypto";
+import { parseSession, findSessionFiles, parseSessionAsync } from "../../src/lib/session-parser.js";
+
+// ── Test Fixtures ──────────────────────────────────────────────────────────
+
+function tmpDir(): string {
+  const dir = join(tmpdir(), `preflight-test-${randomUUID()}`);
+  mkdirSync(dir, { recursive: true });
+  return dir;
+}
+
+function writeJsonl(dir: string, name: string, records: any[]): string {
+  const p = join(dir, name);
+  writeFileSync(p, records.map((r) => JSON.stringify(r)).join("\n") + "\n");
+  return p;
+}
+
+const USER_MSG = (text: string) => ({
+  type: "user",
+  timestamp: "2025-01-15T10:00:00Z",
+  message: { content: text },
+});
+
+const ASSISTANT_MSG = (text: string) => ({
+  type: "assistant",
+  timestamp: "2025-01-15T10:00:05Z",
+  message: { content: [{ type: "text", text }] },
+});
+
+const TOOL_CALL_MSG = (toolName: string, input: any, text?: string) => ({
+  type: "assistant",
+  timestamp: "2025-01-15T10:00:10Z",
+  message: {
+    content: [
+      ...(text ? [{ type: "text", text }] : []),
+      { type: "tool_use", name: toolName, input },
+    ],
+  },
+});
+
+const TOOL_RESULT = (content: string, isError = false) => ({
+  type: "tool_result",
+  timestamp: "2025-01-15T10:00:15Z",
+  content,
+  is_error: isError,
+  tool_use_id: "tu_123",
+});
+
+const SUMMARY = (branch?: string, sessionId?: string) => ({
+  type: "summary",
+  ...(branch && { gitBranch: branch }),
+  ...(sessionId && { sessionId }),
+});
+
+const SYSTEM_COMPACT = () => ({
+  type: "system",
+  timestamp: "2025-01-15T10:05:00Z",
+  subtype: "compaction",
+  content: "context compacted",
+});
+
+// ── Tests ──────────────────────────────────────────────────────────────────
+
+describe("parseSession", () => {
+  let dir: string;
+
+  beforeEach(() => {
+    dir = tmpDir();
+  });
+
+  afterEach(() => {
+    rmSync(dir, { recursive: true, force: true });
+  });
+
+  it("parses user prompts into prompt events", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      USER_MSG("fix the auth bug in src/auth.ts"),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    expect(events).toHaveLength(1);
+    expect(events[0].type).toBe("prompt");
+    expect(events[0].content).toBe("fix the auth bug in src/auth.ts");
+    expect(events[0].project).toBe("/test");
+    expect(events[0].project_name).toBe("test");
+  });
+
+  it("parses assistant text responses", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      ASSISTANT_MSG("I'll fix that for you"),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    expect(events).toHaveLength(1);
+    expect(events[0].type).toBe("assistant");
+    expect(events[0].content).toBe("I'll fix that for you");
+  });
+
+  it("extracts tool calls as tool_call events", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      TOOL_CALL_MSG("Read", { file_path: "src/auth.ts" }),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    const toolEvents = events.filter((e) => e.type === "tool_call");
+    expect(toolEvents).toHaveLength(1);
+    expect(toolEvents[0].content).toContain("Read");
+  });
+
+  it("detects sub_agent_spawn for Task tool calls", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      TOOL_CALL_MSG("Task", { description: "fix auth" }),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    const spawns = events.filter((e) => e.type === "sub_agent_spawn");
+    expect(spawns).toHaveLength(1);
+  });
+
+  it("detects sub_agent_spawn for dispatch_agent tool calls", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      TOOL_CALL_MSG("dispatch_agent", { task: "review PR" }),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    const spawns = events.filter((e) => e.type === "sub_agent_spawn");
+    expect(spawns).toHaveLength(1);
+  });
+
+  it("detects corrections after assistant messages", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      ASSISTANT_MSG("Here's the fix"),
+      USER_MSG("no, that's wrong"),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    const corrections = events.filter((e) => e.type === "correction");
+    expect(corrections).toHaveLength(1);
+    expect(corrections[0].content).toBe("no, that's wrong");
+  });
+
+  it("does not flag first user message as correction", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      USER_MSG("no, fix the other file"),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    // No preceding assistant → should be a prompt, not correction
+    expect(events[0].type).toBe("prompt");
+  });
+
+  it("detects error tool results", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      TOOL_RESULT("ENOENT: no such file", true),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    expect(events).toHaveLength(1);
+    expect(events[0].type).toBe("error");
+  });
+
+  it("detects compaction events", () => {
+    const file = writeJsonl(dir, "test.jsonl", [SYSTEM_COMPACT()]);
+    const events = parseSession(file, "/test", "test");
+    expect(events).toHaveLength(1);
+    expect(events[0].type).toBe("compaction");
+  });
+
+  it("picks up branch and sessionId from summary records", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      SUMMARY("feature/auth", "sess-abc"),
+      USER_MSG("hello"),
+    ]);
+    const events = parseSession(file, "/test", "test");
+    expect(events).toHaveLength(1);
+    expect(events[0].branch).toBe("feature/auth");
+    expect(events[0].session_id).toBe("sess-abc");
+  });
+
+  it("handles malformed JSON lines gracefully", () => {
+    const p = join(dir, "bad.jsonl");
+    writeFileSync(p, '{"type":"user","message":{"content":"ok"},"timestamp":"2025-01-15T10:00:00Z"}\nNOT_JSON\n');
+    const events = parseSession(p, "/test", "test");
+    expect(events).toHaveLength(1); // skips bad line
+  });
+
+  it("handles empty file", () => {
+    const p = join(dir, "empty.jsonl");
+    writeFileSync(p, "");
+    const events = parseSession(p, "/test", "test");
+    expect(events).toHaveLength(0);
+  });
+
+  it("normalizes epoch seconds timestamps", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      { type: "user", timestamp: 1705312800, message: { content: "hello" } },
+    ]);
+    const events = parseSession(file, "/test", "test");
+    expect(events[0].timestamp).toMatch(/^\d{4}-\d{2}-\d{2}T/);
+  });
+
+  it("normalizes epoch milliseconds timestamps", () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      { type: "user", timestamp: 1705312800000, message: { content: "hi" } },
+    ]);
+    const events = parseSession(file, "/test", "test");
+    expect(events[0].timestamp).toMatch(/^\d{4}-\d{2}-\d{2}T/);
+  });
+
+  it("generates content_preview truncated to ~120 chars", () => {
+    const longText = "A".repeat(200);
+    const file = writeJsonl(dir, "test.jsonl", [USER_MSG(longText)]);
+    const events = parseSession(file, "/test", "test");
+    expect(events[0].content_preview.length).toBeLessThanOrEqual(121); // 120 + "…"
+    expect(events[0].content_preview).toContain("…");
+  });
+});
+
+describe("parseSessionAsync", () => {
+  let dir: string;
+
+  beforeEach(() => {
+    dir = tmpDir();
+  });
+
+  afterEach(() => {
+    rmSync(dir, { recursive: true, force: true });
+  });
+
+  it("produces same events as sync parser", async () => {
+    const file = writeJsonl(dir, "test.jsonl", [
+      SUMMARY("main"),
+      USER_MSG("do the thing"),
+      ASSISTANT_MSG("done"),
+      USER_MSG("wrong, undo that"),
+    ]);
+    const syncEvents = parseSession(file, "/p", "p");
+    const asyncEvents = await parseSessionAsync(file, "/p", "p");
+    expect(asyncEvents.length).toBe(syncEvents.length);
+    expect(asyncEvents.map((e) => e.type)).toEqual(syncEvents.map((e) => e.type));
+  });
+});
+
+describe("findSessionFiles", () => {
+  let dir: string;
+
+  beforeEach(() => {
+    dir = tmpDir();
+  });
+
+  afterEach(() => {
+    rmSync(dir, { recursive: true, force: true });
+  });
+
+  it("finds .jsonl files in root directory", () => {
+    writeFileSync(join(dir, "session1.jsonl"), "{}");
+    writeFileSync(join(dir, "session2.jsonl"), "{}");
+    writeFileSync(join(dir, "readme.txt"), "not a session");
+    const files = findSessionFiles(dir);
+    expect(files).toHaveLength(2);
+    expect(files.every((f) => f.path.endsWith(".jsonl"))).toBe(true);
+  });
+
+  it("finds subagent session files", () => {
+    const subDir = join(dir, "parent-session", "subagents");
+    mkdirSync(subDir, { recursive: true });
+    writeFileSync(join(subDir, "sub1.jsonl"), "{}");
+    const files = findSessionFiles(dir);
+    expect(files).toHaveLength(1);
+    expect(files[0].sessionId).toBe("sub1");
+  });
+
+  it("returns empty for non-existent directory", () => {
+    const files = findSessionFiles("/nonexistent/path");
+    expect(files).toHaveLength(0);
+  });
+});