diff --git a/src/client/components/AgentProgressView.test.tsx b/src/client/components/AgentProgressView.test.tsx
new file mode 100644
index 0000000..91d67ac
--- /dev/null
+++ b/src/client/components/AgentProgressView.test.tsx
@@ -0,0 +1,254 @@
+// @vitest-environment jsdom
+import { describe, it, expect, vi } from "vitest";
+import React from "react";
+import { render, fireEvent } from "@testing-library/react";
+import "@testing-library/jest-dom";
+import { AgentProgressView } from "./AgentProgressView";
+import type { ParsedMessage } from "../lib/types";
+
+// Mock markdown renderer to avoid pulling in marked/hljs in jsdom
+vi.mock("../lib/markdown", () => ({
+  renderMarkdown: (text: string) => `<p>${text}</p>`,
+}));
+
+/** Build a ParsedMessage whose content is a JSON agent_progress payload */
+function makeAgentProgressEvent(
+  messageOverrides: Record<string, unknown> = {},
+  dataOverrides: Record<string, unknown> = {},
+  msgOverrides: Partial<ParsedMessage> = {}
+): ParsedMessage {
+  const data = {
+    message: {
+      type: "assistant",
+      message: {
+        role: "assistant",
+        content: [
+          {
+            type: "tool_use",
+            id: "toolu_abc",
+            name: "Read",
+            input: { file_path: "/src/foo.ts" },
+          },
+        ],
+      },
+      timestamp: "2026-01-30T16:22:21.000Z",
+      ...messageOverrides,
+    },
+    normalizedMessages: [],
+    type: "agent_progress",
+    prompt: "Explore the codebase",
+    agentId: "a6945d4",
+    ...dataOverrides,
+  };
+
+  return {
+    uuid: crypto.randomUUID(),
+    category: "hook_progress",
+    content: JSON.stringify(data),
+    rawIndex: 0,
+    timestamp: "2026-01-30T16:22:21.000Z",
+    progressSubtype: "agent",
+    ...msgOverrides,
+  };
+}
+
+describe("AgentProgressView", () => {
+  it("renders prompt banner with truncated prompt text", () => {
+    const events = [makeAgentProgressEvent()];
+    const { getByTestId } = render(<AgentProgressView events={events} />);
+
+    const prompt = getByTestId("agent-prompt");
+    expect(prompt.textContent).toContain("Explore the codebase");
+  });
+
+  it("renders agent ID and turn count in header", () => {
+    const events = [makeAgentProgressEvent()];
+    const { getByTestId } = render(<AgentProgressView events={events} />);
+
+    const view = getByTestId("agent-progress-view");
+    expect(view.textContent).toContain("a6945d4");
+    expect(view.textContent).toContain("1 turn");
+  });
+
+  it("renders summary rows with timestamps and tool names", () => {
+    const events = [makeAgentProgressEvent()];
+    const { getAllByTestId } = render(<AgentProgressView events={events} />);
+
+    const rows = getAllByTestId("agent-event-row");
+    expect(rows.length).toBe(1);
+    // Should contain tool name "Read" and the file path
+    expect(rows[0].textContent).toContain("Read");
+    expect(rows[0].textContent).toContain("src/foo.ts");
+  });
+
+  it("summary row for Read shows file path", () => {
+    const events = [
+      makeAgentProgressEvent({
+        message: {
+          role: "assistant",
+          content: [
+            {
+              type: "tool_use",
+              id: "t1",
+              name: "Read",
+              input: { file_path: "/src/components/App.tsx" },
+            },
+          ],
+        },
+      }),
+    ];
+    const { getAllByTestId } = render(<AgentProgressView events={events} />);
+    const rows = getAllByTestId("agent-event-row");
+    expect(rows[0].textContent).toContain("src/components/App.tsx");
+  });
+
+  it("summary row for text response shows line count", () => {
+    const events = [
+      makeAgentProgressEvent({
+        type: "assistant",
+        message: {
+          role: "assistant",
+          content: [
+            { type: "text", text: "Line 1\nLine 2\nLine 3" },
+          ],
+        },
+      }),
+    ];
+    const { getAllByTestId } = render(<AgentProgressView events={events} />);
+    const rows = getAllByTestId("agent-event-row");
+    expect(rows[0].textContent).toContain("3 lines");
+  });
+
+  it("clicking a summary row expands drill-down panel", () => {
+    const events = [makeAgentProgressEvent()];
+    const { getAllByTestId, queryByTestId } = render(
+      <AgentProgressView events={events} />
+    );
+
+    // Initially no drill-down
+    expect(queryByTestId("agent-drilldown")).toBeNull();
+
+    // Click to expand
+    fireEvent.click(getAllByTestId("agent-event-row")[0]);
+    expect(queryByTestId("agent-drilldown")).toBeInTheDocument();
+  });
+
+  it("drill-down shows pretty-printed tool input JSON", () => {
+    const events = [makeAgentProgressEvent()];
+    const { getAllByTestId, getByTestId } = render(
+      <AgentProgressView events={events} />
+    );
+
+    fireEvent.click(getAllByTestId("agent-event-row")[0]);
+    const drilldown = getByTestId("agent-drilldown");
+    expect(drilldown.textContent).toContain("file_path");
+    expect(drilldown.textContent).toContain("/src/foo.ts");
+  });
+
+  it("drill-down shows full tool result content", () => {
+    const events = [
+      makeAgentProgressEvent({
+        type: "user",
+        message: {
+          role: "user",
+          content: [
+            {
+              type: "tool_result",
+              tool_use_id: "toolu_abc",
+              content: "Full file contents here",
+            },
+          ],
+        },
+      }),
+    ];
+    const { getAllByTestId, getByTestId } = render(
+      <AgentProgressView events={events} />
+    );
+
+    fireEvent.click(getAllByTestId("agent-event-row")[0]);
+    const drilldown = getByTestId("agent-drilldown");
+    expect(drilldown.textContent).toContain("Full file contents here");
+  });
+
+  it("clicking expanded row collapses it", () => {
+    const events = [makeAgentProgressEvent()];
+    const { getAllByTestId, queryByTestId } = render(
+      <AgentProgressView events={events} />
+    );
+
+    // Expand
+    fireEvent.click(getAllByTestId("agent-event-row")[0]);
+    expect(queryByTestId("agent-drilldown")).toBeInTheDocument();
+
+    // Collapse
+    fireEvent.click(getAllByTestId("agent-event-row")[0]);
+    expect(queryByTestId("agent-drilldown")).toBeNull();
+  });
+
+  it("only one drill-down open at a time (accordion behavior)", () => {
+    const events = [
+      makeAgentProgressEvent(
+        {
+          message: {
+            role: "assistant",
+            content: [
+              { type: "tool_use", id: "t1", name: "Read", input: { file_path: "/a.ts" } },
+            ],
+          },
+        },
+        {},
+        { uuid: "ev-1" }
+      ),
+      makeAgentProgressEvent(
+        {
+          message: {
+            role: "assistant",
+            content: [
+              { type: "tool_use", id: "t2", name: "Grep", input: { pattern: "foo" } },
+            ],
+          },
+        },
+        {},
+        { uuid: "ev-2" }
+      ),
+    ];
+    const { getAllByTestId } = render(
+      <AgentProgressView events={events} />
+    );
+
+    const rows = getAllByTestId("agent-event-row");
+
+    // Expand first
+    fireEvent.click(rows[0]);
+    let drilldowns = getAllByTestId("agent-drilldown");
+    expect(drilldowns.length).toBe(1);
+
+    // Click second - should close first and open second
+    fireEvent.click(rows[1]);
+    drilldowns = getAllByTestId("agent-drilldown");
+    expect(drilldowns.length).toBe(1);
+    // Second drill-down should show Grep pattern
+    expect(drilldowns[0].textContent).toContain("foo");
+  });
+
+  it("handles events with missing timestamps gracefully", () => {
+    const events = [
+      makeAgentProgressEvent(
+        {
+          message: {
+            role: "assistant",
+            content: [
+              { type: "tool_use", id: "t1", name: "Read", input: { file_path: "/a.ts" } },
+            ],
+          },
+          timestamp: undefined,
+        },
+        {},
+        { timestamp: undefined }
+      ),
+    ];
+    // Should render without crashing
+    const { getByTestId } = render(<AgentProgressView events={events} />);
+    expect(getByTestId("agent-progress-view")).toBeInTheDocument();
+  });
+});
diff --git a/src/client/components/ProgressBadge.test.tsx b/src/client/components/ProgressBadge.test.tsx
new file mode 100644
index 0000000..a33d971
--- /dev/null
+++ b/src/client/components/ProgressBadge.test.tsx
@@ -0,0 +1,240 @@
+// @vitest-environment jsdom
+import { describe, it, expect, vi } from "vitest";
+import React from "react";
+import { render, fireEvent } from "@testing-library/react";
+import "@testing-library/jest-dom";
+import { ProgressBadge } from "./ProgressBadge";
+import type { ParsedMessage } from "../lib/types";
+
+// Mock the markdown module to avoid pulling in marked/hljs in jsdom
+vi.mock("../lib/markdown", () => ({
+  renderMarkdown: (text: string) => `<p>${text}</p>`,
+}));
+
+function makeEvent(
+  overrides: Partial<ParsedMessage> = {}
+): ParsedMessage {
+  return {
+    uuid: crypto.randomUUID(),
+    category: "hook_progress",
+    content: "Running pre-commit hook",
+    rawIndex: 0,
+    timestamp: "2025-01-15T10:30:00Z",
+    progressSubtype: "hook",
+    ...overrides,
+  };
+}
+
+describe("ProgressBadge", () => {
+  describe("collapsed state", () => {
+    it("shows pill counts but hides event content", () => {
+      const events = [
+        makeEvent({ progressSubtype: "hook" }),
+        makeEvent({ progressSubtype: "hook" }),
+        makeEvent({ progressSubtype: "bash" }),
+      ];
+      const { container, queryByText } = render(
+        <ProgressBadge events={events} />
+      );
+
+      // Pill counts visible
+      expect(container.textContent).toContain("hook: 2");
+      expect(container.textContent).toContain("bash: 1");
+
+      // Event content should NOT be visible when collapsed
+      expect(queryByText("Running pre-commit hook")).toBeNull();
+    });
+  });
+
+  describe("expanded state", () => {
+    it("shows all event content when clicked", () => {
+      const events = [
+        makeEvent({ content: "First event" }),
+        makeEvent({ content: "Second event" }),
+      ];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      // Click to expand
+      fireEvent.click(container.querySelector("button")!);
+
+      // Content should be visible (rendered as markdown via mock)
+      expect(container.innerHTML).toContain("First event");
+      expect(container.innerHTML).toContain("Second event");
+    });
+
+    it("renders content through markdown into prose-message-progress container", () => {
+      const events = [
+        makeEvent({ content: "**bold text**" }),
+      ];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      // Expand
+      fireEvent.click(container.querySelector("button")!);
+
+      // Our mock wraps in <p>, so the prose container should have rendered HTML
+      const proseEl = container.querySelector(".prose-message-progress");
+      expect(proseEl).toBeInTheDocument();
+      // Content is from local JSONL session files owned by the user,
+      // same trust model as MessageBubble's markdown rendering
+      expect(proseEl?.innerHTML).toContain("<p>**bold text**</p>");
+    });
+
+    it("does not have max-h-48 or overflow-y-auto on expanded container", () => {
+      const events = [makeEvent()];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      fireEvent.click(container.querySelector("button")!);
+
+      const expandedDiv = container.querySelector("[data-testid='progress-expanded']");
+      expect(expandedDiv).toBeInTheDocument();
+      expect(expandedDiv?.className).not.toContain("max-h-48");
+      expect(expandedDiv?.className).not.toContain("overflow-y-auto");
+    });
+
+    it("does not have truncate class on content", () => {
+      const events = [makeEvent()];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      fireEvent.click(container.querySelector("button")!);
+
+      // Generic (non-agent) expanded view should not truncate
+      const proseElements = container.querySelectorAll(".prose-message-progress");
+      for (const el of proseElements) {
+        expect(el.className).not.toContain("truncate");
+      }
+    });
+
+    it("displays timestamps and subtype badges per event", () => {
+      const events = [
+        makeEvent({
+          timestamp: "2025-01-15T10:30:00Z",
+          progressSubtype: "bash",
+          content: "npm test",
+        }),
+      ];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      fireEvent.click(container.querySelector("button")!);
+
+      // Subtype badge visible
+      expect(container.textContent).toContain("bash");
+      // Timestamp visible (formatted by toLocaleTimeString)
+      const expandedDiv = container.querySelector("[data-testid='progress-expanded']");
+      expect(expandedDiv).toBeInTheDocument();
+      // The timestamp text should exist somewhere in the expanded area
+      expect(expandedDiv?.textContent).toMatch(/\d{1,2}:\d{2}:\d{2}/);
+    });
+  });
+
+  describe("edge cases", () => {
+    it("handles empty events array", () => {
+      const { container } = render(<ProgressBadge events={[]} />);
+      // Should render without crashing, no pills
+      expect(container.querySelector("button")).toBeInTheDocument();
+    });
+
+    it("handles missing timestamps", () => {
+      const events = [makeEvent({ timestamp: undefined })];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      fireEvent.click(container.querySelector("button")!);
+
+      expect(container.textContent).toContain("--:--:--");
+    });
+
+    it("defaults undefined subtype to hook", () => {
+      const events = [makeEvent({ progressSubtype: undefined })];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      // In pill counts
+      expect(container.textContent).toContain("hook: 1");
+    });
+  });
+
+  describe("agent subtype delegation", () => {
+    function makeAgentEvent(
+      overrides: Partial<ParsedMessage> = {}
+    ): ParsedMessage {
+      const data = {
+        message: {
+          type: "assistant",
+          message: {
+            role: "assistant",
+            content: [
+              {
+                type: "tool_use",
+                id: "toolu_abc",
+                name: "Read",
+                input: { file_path: "/src/foo.ts" },
+              },
+            ],
+          },
+          timestamp: "2026-01-30T16:22:21.000Z",
+        },
+        type: "agent_progress",
+        prompt: "Explore the codebase",
+        agentId: "a6945d4",
+      };
+
+      return {
+        uuid: crypto.randomUUID(),
+        category: "hook_progress",
+        content: JSON.stringify(data),
+        rawIndex: 0,
+        timestamp: "2026-01-30T16:22:21.000Z",
+        progressSubtype: "agent",
+        ...overrides,
+      };
+    }
+
+    it("renders AgentProgressView when all events are agent subtype", () => {
+      const events = [makeAgentEvent(), makeAgentEvent()];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      // Expand
+      fireEvent.click(container.querySelector("button")!);
+
+      // Should render AgentProgressView
+      expect(
+        container.querySelector("[data-testid='agent-progress-view']")
+      ).toBeInTheDocument();
+      // Should NOT render generic prose-message-progress
+      expect(
+        container.querySelector(".prose-message-progress")
+      ).toBeNull();
+    });
+
+    it("renders generic list when events are mixed subtypes", () => {
+      const events = [
+        makeAgentEvent(),
+        makeEvent({ progressSubtype: "hook" }),
+      ];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      // Expand
+      fireEvent.click(container.querySelector("button")!);
+
+      // Should NOT render AgentProgressView
+      expect(
+        container.querySelector("[data-testid='agent-progress-view']")
+      ).toBeNull();
+      // Should render generic view
+      expect(
+        container.querySelector(".prose-message-progress")
+      ).toBeInTheDocument();
+    });
+
+    it("pills and collapsed state unchanged regardless of subtype", () => {
+      const events = [makeAgentEvent(), makeAgentEvent(), makeAgentEvent()];
+      const { container } = render(<ProgressBadge events={events} />);
+
+      // Pills show agent count
+      expect(container.textContent).toContain("agent: 3");
+
+      // No expanded content initially
+      expect(
+        container.querySelector("[data-testid='progress-expanded']")
+      ).toBeNull();
+    });
+  });
+});
diff --git a/tests/fixtures/sample-session.jsonl b/tests/fixtures/sample-session.jsonl
index f683819..24daa03 100644
--- a/tests/fixtures/sample-session.jsonl
+++ b/tests/fixtures/sample-session.jsonl
@@ -1,14 +1,18 @@
 {"type":"file-history-snapshot","messageId":"snap-1","snapshot":{"messageId":"snap-1","trackedFileBackups":[],"timestamp":"2025-10-15T10:30:00Z"},"isSnapshotUpdate":false}
-{"type":"progress","data":{"type":"hook","hookEvent":"PreToolUse","hookName":"security_check","command":"check"},"uuid":"prog-1","timestamp":"2025-10-15T10:30:01Z"}
+{"type":"progress","data":{"type":"hook_progress","hookEvent":"SessionStart","hookName":"init_hook","command":"setup"},"uuid":"prog-0","timestamp":"2025-10-15T10:30:00Z"}
+{"type":"progress","data":{"type":"hook_progress","hookEvent":"PreToolUse","hookName":"security_check","command":"check"},"uuid":"prog-1","timestamp":"2025-10-15T10:30:01Z"}
 {"type":"user","message":{"role":"user","content":"Can you help me fix the login bug? Users are getting a 401 error."},"uuid":"msg-1","timestamp":"2025-10-15T10:30:05Z"}
 {"type":"assistant","message":{"role":"assistant","content":[{"type":"thinking","thinking":"The user is reporting a 401 error on login. I should look at the authentication middleware and the login endpoint to understand what's happening."},{"type":"text","text":"I'll investigate the login bug. Let me start by looking at the authentication code."}]},"uuid":"msg-2","timestamp":"2025-10-15T10:30:10Z"}
-{"type":"assistant","message":{"role":"assistant","content":[{"type":"tool_use","name":"Read","input":{"file_path":"/src/auth/login.ts"}}]},"uuid":"msg-3","timestamp":"2025-10-15T10:30:15Z"}
-{"type":"user","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"toolu_01","content":"export async function login(email: string, password: string) {\n  const user = await db.users.findByEmail(email);\n  if (!user) throw new UnauthorizedError();\n  const valid = await bcrypt.compare(password, user.passwordHash);\n  if (!valid) throw new UnauthorizedError();\n  return generateToken(user);\n}"}]},"uuid":"msg-4","timestamp":"2025-10-15T10:30:16Z"}
+{"type":"assistant","message":{"role":"assistant","content":[{"type":"tool_use","id":"toolu_read1","name":"Read","input":{"file_path":"/src/auth/login.ts"}}]},"uuid":"msg-3","timestamp":"2025-10-15T10:30:15Z"}
+{"type":"progress","data":{"type":"hook_progress","hookEvent":"PreToolUse","hookName":"read_hook","status":"callback"},"parentToolUseID":"toolu_read1","uuid":"prog-read-hook","timestamp":"2025-10-15T10:30:15Z"}
+{"type":"user","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"toolu_read1","content":"export async function login(email: string, password: string) {\n  const user = await db.users.findByEmail(email);\n  if (!user) throw new UnauthorizedError();\n  const valid = await bcrypt.compare(password, user.passwordHash);\n  if (!valid) throw new UnauthorizedError();\n  return generateToken(user);\n}"}]},"uuid":"msg-4","timestamp":"2025-10-15T10:30:16Z"}
 {"type":"assistant","message":{"role":"assistant","content":[{"type":"text","text":"I found the issue. The `login` function looks correct, but let me check the middleware that validates tokens.\n\n```typescript\n// The fix is to update the token validation\nexport function validateToken(token: string) {\n  return jwt.verify(token, process.env.JWT_SECRET!);\n}\n```\n\nThe problem was that the JWT_SECRET environment variable wasn't being loaded properly."}]},"uuid":"msg-5","timestamp":"2025-10-15T10:30:20Z"}
 {"type":"user","message":{"role":"user","content":"<system-reminder>Remember to check environment variables</system-reminder>"},"uuid":"msg-6","timestamp":"2025-10-15T10:30:21Z"}
 {"type":"user","message":{"role":"user","content":"That makes sense! Can you fix it?"},"uuid":"msg-7","timestamp":"2025-10-15T10:31:00Z"}
-{"type":"assistant","message":{"role":"assistant","content":[{"type":"tool_use","name":"Edit","input":{"file_path":"/src/auth/middleware.ts","old_string":"jwt.verify(token, process.env.JWT_SECRET!)","new_string":"jwt.verify(token, getJwtSecret())"}}]},"uuid":"msg-8","timestamp":"2025-10-15T10:31:05Z"}
-{"type":"user","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"toolu_02","content":"File edited successfully."}]},"uuid":"msg-9","timestamp":"2025-10-15T10:31:06Z"}
+{"type":"assistant","message":{"role":"assistant","content":[{"type":"tool_use","id":"toolu_edit1","name":"Edit","input":{"file_path":"/src/auth/middleware.ts","old_string":"jwt.verify(token, process.env.JWT_SECRET!)","new_string":"jwt.verify(token, getJwtSecret())"}}]},"uuid":"msg-8","timestamp":"2025-10-15T10:31:05Z"}
+{"type":"progress","data":{"type":"bash_progress","status":"running","toolName":"Bash"},"parentToolUseID":"toolu_edit1","uuid":"prog-edit-bash","timestamp":"2025-10-15T10:31:05Z"}
+{"type":"progress","data":{"type":"mcp_progress","serverName":"morph-mcp","toolName":"edit_file","status":"completed"},"parentToolUseID":"toolu_edit1","uuid":"prog-edit-mcp","timestamp":"2025-10-15T10:31:06Z"}
+{"type":"user","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"toolu_edit1","content":"File edited successfully."}]},"uuid":"msg-9","timestamp":"2025-10-15T10:31:06Z"}
 {"type":"assistant","message":{"role":"assistant","content":[{"type":"text","text":"I've fixed the issue by using a `getJwtSecret()` helper that properly loads and caches the secret. The login should work now."}]},"uuid":"msg-10","timestamp":"2025-10-15T10:31:10Z"}
 {"type":"progress","data":{"type":"tool","status":"running","toolName":"Bash","serverName":"local"},"uuid":"prog-2","timestamp":"2025-10-15T10:31:15Z"}
 {"type":"summary","summary":"Fixed authentication bug by updating JWT secret loading in middleware.","leafUuid":"msg-10"}
diff --git a/tests/unit/agent-progress-parser.test.ts b/tests/unit/agent-progress-parser.test.ts
new file mode 100644
index 0000000..5defc6b
--- /dev/null
+++ b/tests/unit/agent-progress-parser.test.ts
@@ -0,0 +1,511 @@
+import { describe, it, expect } from "vitest";
+import {
+  parseAgentEvents,
+  summarizeToolCall,
+  stripLineNumbers,
+} from "../../src/client/lib/agent-progress-parser";
+import type { ParsedMessage } from "../../src/shared/types";
+
+/** Build a fake ParsedMessage whose content is a JSON agent_progress payload */
+function makeAgentEvent(
+  dataOverrides: Record<string, unknown> = {},
+  msgOverrides: Partial<ParsedMessage> = {}
+): ParsedMessage {
+  const data = {
+    message: {
+      type: "assistant",
+      message: {
+        role: "assistant",
+        content: [
+          {
+            type: "tool_use",
+            id: "toolu_abc123",
+            name: "Read",
+            input: { file_path: "/src/foo.ts" },
+          },
+        ],
+      },
+      timestamp: "2026-01-30T16:22:21.000Z",
+    },
+    normalizedMessages: [],
+    type: "agent_progress",
+    prompt: "Explore the codebase",
+    agentId: "a6945d4",
+    ...dataOverrides,
+  };
+
+  return {
+    uuid: crypto.randomUUID(),
+    category: "hook_progress",
+    content: JSON.stringify(data),
+    rawIndex: 0,
+    timestamp: "2026-01-30T16:22:21.000Z",
+    progressSubtype: "agent",
+    ...msgOverrides,
+  };
+}
+
+describe("agent-progress-parser", () => {
+  describe("parseAgentEvents", () => {
+    it("parses a user text event and extracts the prompt", () => {
+      const event = makeAgentEvent({
+        message: {
+          type: "user",
+          message: {
+            role: "user",
+            content: [
+              { type: "text", text: "Find the auth implementation" },
+            ],
+          },
+          timestamp: "2026-01-30T16:22:00.000Z",
+        },
+      });
+
+      const result = parseAgentEvents([event]);
+      expect(result.prompt).toBe("Explore the codebase");
+      expect(result.agentId).toBe("a6945d4");
+      expect(result.events.length).toBe(1);
+      expect(result.events[0].kind).toBe("user_text");
+      if (result.events[0].kind === "user_text") {
+        expect(result.events[0].text).toBe("Find the auth implementation");
+      }
+    });
+
+    it("parses assistant turn with tool_use blocks and extracts tool info", () => {
+      const event = makeAgentEvent(); // default has Read tool_use
+
+      const result = parseAgentEvents([event]);
+      expect(result.events.length).toBe(1);
+      expect(result.events[0].kind).toBe("tool_call");
+      if (result.events[0].kind === "tool_call") {
+        expect(result.events[0].toolName).toBe("Read");
+        expect(result.events[0].toolUseId).toBe("toolu_abc123");
+        expect(result.events[0].input).toEqual({ file_path: "/src/foo.ts" });
+      }
+    });
+
+    it("parses user turn with tool_result and extracts result content", () => {
+      const event = makeAgentEvent({
+        message: {
+          type: "user",
+          message: {
+            role: "user",
+            content: [
+              {
+                type: "tool_result",
+                tool_use_id: "toolu_abc123",
+                content: "File contents here...",
+              },
+            ],
+          },
+          timestamp: "2026-01-30T16:22:22.000Z",
+        },
+      });
+
+      const result = parseAgentEvents([event]);
+      expect(result.events[0].kind).toBe("tool_result");
+      if (result.events[0].kind === "tool_result") {
+        expect(result.events[0].toolUseId).toBe("toolu_abc123");
+        expect(result.events[0].content).toBe("File contents here...");
+      }
+    });
+
+    it("parses assistant turn with text content as text_response", () => {
+      const event = makeAgentEvent({
+        message: {
+          type: "assistant",
+          message: {
+            role: "assistant",
+            content: [
+              { type: "text", text: "Here is my analysis of the codebase.\nLine 2\nLine 3\nLine 4" },
+            ],
+          },
+          timestamp: "2026-01-30T16:22:30.000Z",
+        },
+      });
+
+      const result = parseAgentEvents([event]);
+      expect(result.events[0].kind).toBe("text_response");
+      if (result.events[0].kind === "text_response") {
+        expect(result.events[0].text).toContain("Here is my analysis");
+        expect(result.events[0].lineCount).toBe(4);
+      }
+    });
+
+    it("extracts agentId and prompt from events", () => {
+      const events = [makeAgentEvent()];
+      const result = parseAgentEvents(events);
+      expect(result.agentId).toBe("a6945d4");
+      expect(result.prompt).toBe("Explore the codebase");
+    });
+
+    it("calculates time range from first/last event timestamps", () => {
+      const events = [
+        makeAgentEvent(
+          {
+            message: {
+              type: "user",
+              message: { role: "user", content: [{ type: "text", text: "Go" }] },
+              timestamp: "2026-01-30T16:22:00.000Z",
+            },
+          },
+          { timestamp: "2026-01-30T16:22:00.000Z" }
+        ),
+        makeAgentEvent(
+          {
+            message: {
+              type: "assistant",
+              message: {
+                role: "assistant",
+                content: [
+                  { type: "tool_use", id: "t1", name: "Read", input: { file_path: "a.ts" } },
+                ],
+              },
+              timestamp: "2026-01-30T16:22:30.000Z",
+            },
+          },
+          { timestamp: "2026-01-30T16:22:30.000Z" }
+        ),
+      ];
+
+      const result = parseAgentEvents(events);
+      expect(result.firstTimestamp).toBe("2026-01-30T16:22:00.000Z");
+      expect(result.lastTimestamp).toBe("2026-01-30T16:22:30.000Z");
+    });
+
+    it("counts turns correctly (tool_call events = turns)", () => {
+      const events = [
+        // User text
+        makeAgentEvent({
+          message: {
+            type: "user",
+            message: { role: "user", content: [{ type: "text", text: "Go" }] },
+            timestamp: "2026-01-30T16:22:00.000Z",
+          },
+        }),
+        // Tool call 1
+        makeAgentEvent({
+          message: {
+            type: "assistant",
+            message: {
+              role: "assistant",
+              content: [
+                { type: "tool_use", id: "t1", name: "Read", input: { file_path: "a.ts" } },
+              ],
+            },
+            timestamp: "2026-01-30T16:22:01.000Z",
+          },
+        }),
+        // Tool result 1
+        makeAgentEvent({
+          message: {
+            type: "user",
+            message: {
+              role: "user",
+              content: [{ type: "tool_result", tool_use_id: "t1", content: "..." }],
+            },
+            timestamp: "2026-01-30T16:22:02.000Z",
+          },
+        }),
+        // Tool call 2
+        makeAgentEvent({
+          message: {
+            type: "assistant",
+            message: {
+              role: "assistant",
+              content: [
+                { type: "tool_use", id: "t2", name: "Grep", input: { pattern: "foo" } },
+              ],
+            },
+            timestamp: "2026-01-30T16:22:03.000Z",
+          },
+        }),
+        // Tool result 2
+        makeAgentEvent({
+          message: {
+            type: "user",
+            message: {
+              role: "user",
+              content: [{ type: "tool_result", tool_use_id: "t2", content: "..." }],
+            },
+            timestamp: "2026-01-30T16:22:04.000Z",
+          },
+        }),
+        // Final text
+        makeAgentEvent({
+          message: {
+            type: "assistant",
+            message: {
+              role: "assistant",
+              content: [{ type: "text", text: "Done" }],
+            },
+            timestamp: "2026-01-30T16:22:05.000Z",
+          },
+        }),
+      ];
+
+      const result = parseAgentEvents(events);
+      expect(result.turnCount).toBe(2); // 2 tool_call events
+    });
+
+    it("handles malformed JSON content gracefully", () => {
+      const event: ParsedMessage = {
+        uuid: "bad-json",
+        category: "hook_progress",
+        content: "this is not valid json {{{",
+        rawIndex: 0,
+        timestamp: "2026-01-30T16:22:00.000Z",
+        progressSubtype: "agent",
+      };
+
+      const result = parseAgentEvents([event]);
+      expect(result.events.length).toBe(1);
+      expect(result.events[0].kind).toBe("raw_content");
+      if (result.events[0].kind === "raw_content") {
+        expect(result.events[0].content).toBe("this is not valid json {{{");
+      }
+    });
+
+    it("handles empty events array", () => {
+      const result = parseAgentEvents([]);
+      expect(result.events).toEqual([]);
+      expect(result.agentId).toBeUndefined();
+      expect(result.prompt).toBeUndefined();
+      expect(result.turnCount).toBe(0);
+    });
+
+    it("handles tool_result with array content blocks", () => {
+      const event = makeAgentEvent({
+        message: {
+          type: "user",
+          message: {
+            role: "user",
+            content: [
+              {
+                type: "tool_result",
+                tool_use_id: "toolu_xyz",
+                content: [
+                  { type: "text", text: "Part 1\n" },
+                  { type: "text", text: "Part 2\n" },
+                ],
+              },
+            ],
+          },
+          timestamp: "2026-01-30T16:22:22.000Z",
+        },
+      });
+
+      const result = parseAgentEvents([event]);
+      expect(result.events[0].kind).toBe("tool_result");
+      if (result.events[0].kind === "tool_result") {
+        expect(result.events[0].content).toBe("Part 1\nPart 2\n");
+      }
+    });
+
+    it("handles multiple tool_use blocks in a single assistant message", () => {
+      const event = makeAgentEvent({
+        message: {
+          type: "assistant",
+          message: {
+            role: "assistant",
+            content: [
+              { type: "tool_use", id: "t1", name: "Read", input: { file_path: "a.ts" } },
+              { type: "tool_use", id: "t2", name: "Read", input: { file_path: "b.ts" } },
+            ],
+          },
+          timestamp: "2026-01-30T16:22:01.000Z",
+        },
+      });
+
+      const result = parseAgentEvents([event]);
+      const toolCalls = result.events.filter((e) => e.kind === "tool_call");
+      expect(toolCalls.length).toBe(2);
+    });
+  });
+
+  describe("summarizeToolCall", () => {
+    it("summarizes Read tool with file_path", () => {
+      const summary = summarizeToolCall("Read", { file_path: "/src/components/App.tsx" });
+      expect(summary).toBe("src/components/App.tsx");
+    });
+
+    it("summarizes Grep tool with pattern + path", () => {
+      const summary = summarizeToolCall("Grep", {
+        pattern: "useChat",
+        path: "/src/hooks/",
+      });
+      expect(summary).toContain("useChat");
+      expect(summary).toContain("src/hooks/");
+    });
+
+    it("summarizes Bash tool with truncated command", () => {
+      const summary = summarizeToolCall("Bash", {
+        command: "npm run test -- --watch --verbose --coverage --reporter=json",
+      });
+      expect(summary.length).toBeLessThanOrEqual(80);
+      expect(summary).toContain("npm run test");
+    });
+
+    it("summarizes Task tool with description", () => {
+      const summary = summarizeToolCall("Task", {
+        description: "Find all auth handlers",
+        subagent_type: "Explore",
+      });
+      expect(summary).toContain("Find all auth handlers");
+    });
+
+    it("summarizes Glob tool with pattern", () => {
+      const summary = summarizeToolCall("Glob", {
+        pattern: "**/*.test.ts",
+        path: "/src/",
+      });
+      expect(summary).toContain("**/*.test.ts");
+    });
+
+    it("summarizes Edit tool with file_path", () => {
+      const summary = summarizeToolCall("Edit", {
+        file_path: "/src/lib/utils.ts",
+        old_string: "foo",
+        new_string: "bar",
+      });
+      expect(summary).toContain("src/lib/utils.ts");
+    });
+
+    it("summarizes Write tool with file_path", () => {
+      const summary = summarizeToolCall("Write", {
+        file_path: "/src/new-file.ts",
+        content: "export const x = 1;",
+      });
+      expect(summary).toContain("src/new-file.ts");
+    });
+
+    it("summarizes unknown tool with generic label", () => {
+      const summary = summarizeToolCall("CustomTool", { foo: "bar" });
+      expect(summary).toBe("CustomTool");
+    });
+
+    it("summarizes mcp__morph-mcp__warpgrep_codebase_search with search_string", () => {
+      const summary = summarizeToolCall("mcp__morph-mcp__warpgrep_codebase_search", {
+        search_string: "Find authentication middleware",
+        repo_path: "/data/projects/app",
+      });
+      expect(summary).toContain("Find authentication middleware");
+    });
+
+    it("summarizes mcp__morph-mcp__edit_file with path", () => {
+      const summary = summarizeToolCall("mcp__morph-mcp__edit_file", {
+        path: "/src/lib/utils.ts",
+        code_edit: "// changes",
+        instruction: "Fix bug",
+      });
+      expect(summary).toContain("src/lib/utils.ts");
+    });
+
+    it("strips leading slash from file paths", () => {
+      const summary = summarizeToolCall("Read", { file_path: "/src/foo.ts" });
+      expect(summary).toBe("src/foo.ts");
+    });
+  });
+
+  describe("stripLineNumbers", () => {
+    it("strips cat-n style line numbers with arrow prefix", () => {
+      const input = "     1\u2192import React from 'react';\n     2\u2192\n     3\u2192export default function App() {";
+      const result = stripLineNumbers(input);
+      expect(result).toBe("import React from 'react';\n\nexport default function App() {");
+    });
+
+    it("returns text unchanged if no line numbers detected", () => {
+      const input = "just plain text\nno line numbers here";
+      expect(stripLineNumbers(input)).toBe(input);
+    });
+
+    it("returns text unchanged for short single-line content", () => {
+      const input = "single line";
+      expect(stripLineNumbers(input)).toBe(input);
+    });
+
+    it("handles double-digit line numbers", () => {
+      const lines = Array.from({ length: 15 }, (_, i) =>
+        `    ${i + 1}\u2192line ${i + 1}`
+      ).join("\n");
+      const result = stripLineNumbers(lines);
+      expect(result).toContain("line 1");
+      expect(result).not.toMatch(/^\s*\d+\u2192/m);
+    });
+  });
+
+  describe("tool_result language linking", () => {
+    it("links tool_result to preceding Read call and sets language", () => {
+      const events = [
+        makeAgentEvent({
+          message: {
+            type: "assistant",
+            message: {
+              role: "assistant",
+              content: [
+                { type: "tool_use", id: "t1", name: "Read", input: { file_path: "/src/app.tsx" } },
+              ],
+            },
+            timestamp: "2026-01-30T16:22:01.000Z",
+          },
+        }),
+        makeAgentEvent({
+          message: {
+            type: "user",
+            message: {
+              role: "user",
+              content: [
+                { type: "tool_result", tool_use_id: "t1", content: "import React..." },
+              ],
+            },
+            timestamp: "2026-01-30T16:22:02.000Z",
+          },
+        }),
+      ];
+
+      const result = parseAgentEvents(events);
+      const toolResult = result.events.find((e) => e.kind === "tool_result");
+      expect(toolResult).toBeDefined();
+      if (toolResult?.kind === "tool_result") {
+        expect(toolResult.language).toBe("tsx");
+        expect(toolResult.sourceTool).toBe("Read");
+      }
+    });
+
+    it("sets no language for Grep results", () => {
+      const events = [
+        makeAgentEvent({
+          message: {
+            type: "assistant",
+            message: {
+              role: "assistant",
+              content: [
+                { type: "tool_use", id: "t1", name: "Grep", input: { pattern: "foo" } },
+              ],
+            },
+            timestamp: "2026-01-30T16:22:01.000Z",
+          },
+        }),
+        makeAgentEvent({
+          message: {
+            type: "user",
+            message: {
+              role: "user",
+              content: [
+                { type: "tool_result", tool_use_id: "t1", content: "src/a.ts:10:foo" },
+              ],
+            },
+            timestamp: "2026-01-30T16:22:02.000Z",
+          },
+        }),
+      ];
+
+      const result = parseAgentEvents(events);
+      const toolResult = result.events.find((e) => e.kind === "tool_result");
+      if (toolResult?.kind === "tool_result") {
+        expect(toolResult.language).toBeUndefined();
+        expect(toolResult.sourceTool).toBe("Grep");
+      }
+    });
+  });
+});
diff --git a/tests/unit/filters.test.ts b/tests/unit/filters.test.ts
index 0b5ce97..2b0b48f 100644
--- a/tests/unit/filters.test.ts
+++ b/tests/unit/filters.test.ts
@@ -112,6 +112,19 @@ describe("filters", () => {
     expect(filtered.every((m) => m.category === "tool_call" || m.category === "tool_result")).toBe(true);
   });
 
+  it("hook_progress included when category is enabled", () => {
+    const enabled = new Set<MessageCategory>(ALL_CATEGORIES);
+    const filtered = filterMessages(messages, enabled);
+    expect(filtered.find((m) => m.category === "hook_progress")).toBeDefined();
+  });
+
+  it("hook_progress excluded when category is disabled", () => {
+    const enabled = new Set<MessageCategory>(ALL_CATEGORIES);
+    enabled.delete("hook_progress");
+    const filtered = filterMessages(messages, enabled);
+    expect(filtered.find((m) => m.category === "hook_progress")).toBeUndefined();
+  });
+
   it("category counts are computed correctly", () => {
     const counts: Record<string, number> = {};
     for (const cat of ALL_CATEGORIES) {
diff --git a/tests/unit/html-exporter.test.ts b/tests/unit/html-exporter.test.ts
index 74d1f38..cf0af62 100644
--- a/tests/unit/html-exporter.test.ts
+++ b/tests/unit/html-exporter.test.ts
@@ -16,13 +16,15 @@ function makeMessage(
 function makeExportRequest(
   messages: ParsedMessage[],
   visible?: string[],
-  redacted?: string[]
+  redacted?: string[],
+  toolProgress?: Record<string, ParsedMessage[]>
 ): ExportRequest {
   return {
     session: {
       id: "test-session",
       project: "test-project",
       messages,
+      toolProgress,
     },
     visibleMessageUuids: visible || messages.map((m) => m.uuid),
     redactedMessageUuids: redacted || [],
@@ -118,4 +120,149 @@ describe("html-exporter", () => {
     // Verify singular — should NOT contain "1 messages"
     expect(html).not.toMatch(/\b1 messages\b/);
   });
+
+  // ─── Collapsible messages ───
+
+  it("thinking messages render collapsed by default", async () => {
+    const msg = makeMessage({
+      uuid: "think-1",
+      category: "thinking",
+      content: "Line one\nLine two\nLine three\nLine four\nLine five",
+    });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    expect(html).toContain('data-collapsed="true"');
+  });
+
+  it("tool_call messages render collapsed with tool name preview", async () => {
+    const msg = makeMessage({
+      uuid: "tc-1",
+      category: "tool_call",
+      content: "",
+      toolName: "Read",
+      toolInput: '{"path": "/foo/bar.ts"}',
+      toolUseId: "tu-1",
+    });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    expect(html).toContain('data-collapsed="true"');
+    expect(html).toContain("collapsed-preview");
+    expect(html).toContain("Read");
+  });
+
+  it("tool_result messages render collapsed with content preview", async () => {
+    const msg = makeMessage({
+      uuid: "tr-1",
+      category: "tool_result",
+      content: "This is the first line of a tool result that should be truncated in the preview display when collapsed",
+    });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    expect(html).toContain('data-collapsed="true"');
+    expect(html).toContain("collapsed-preview");
+  });
+
+  it("collapsible messages include toggle button", async () => {
+    const msg = makeMessage({
+      uuid: "think-2",
+      category: "thinking",
+      content: "Some thoughts",
+    });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    expect(html).toContain("collapsible-toggle");
+  });
+
+  it("non-collapsible messages do not have collapse attributes on their message div", async () => {
+    const msg = makeMessage({
+      uuid: "user-1",
+      category: "user_message",
+      content: "Hello there",
+    });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    // Extract the message div — it should NOT have data-collapsed (CSS will have it as a selector)
+    const messageDiv = html.match(/<div class="message"[^>]*>/);
+    expect(messageDiv).not.toBeNull();
+    expect(messageDiv![0]).not.toContain("data-collapsed");
+    expect(messageDiv![0]).not.toContain("collapsible-toggle");
+  });
+
+  it("export includes toggle JavaScript", async () => {
+    const msg = makeMessage({ uuid: "msg-js", content: "Hello" });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    expect(html).toContain("<script>");
+    expect(html).toContain("collapsible-toggle");
+  });
+
+  it("tool_result with diff content gets diff highlighting", async () => {
+    const diffContent = [
+      "diff --git a/foo.ts b/foo.ts",
+      "--- a/foo.ts",
+      "+++ b/foo.ts",
+      "@@ -1,3 +1,3 @@",
+      " unchanged",
+      "-old line",
+      "+new line",
+    ].join("\n");
+    const msg = makeMessage({
+      uuid: "tr-diff",
+      category: "tool_result",
+      content: diffContent,
+    });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    expect(html).toContain("diff-add");
+    expect(html).toContain("diff-del");
+    expect(html).toContain("diff-hunk");
+  });
+
+  it("tool_call with progress events renders progress badge", async () => {
+    const toolMsg = makeMessage({
+      uuid: "tc-prog",
+      category: "tool_call",
+      content: "",
+      toolName: "Bash",
+      toolUseId: "tu-prog",
+    });
+    const progressEvents: ParsedMessage[] = [
+      makeMessage({
+        uuid: "pe-1",
+        category: "hook_progress",
+        content: "Running...",
+        progressSubtype: "bash",
+        timestamp: "2025-01-01T12:00:00Z",
+      }),
+      makeMessage({
+        uuid: "pe-2",
+        category: "hook_progress",
+        content: "Done",
+        progressSubtype: "bash",
+        timestamp: "2025-01-01T12:00:01Z",
+      }),
+    ];
+    const html = await generateExportHtml(
+      makeExportRequest([toolMsg], undefined, undefined, { "tu-prog": progressEvents })
+    );
+    expect(html).toContain("progress-badge");
+    expect(html).toContain("progress-drawer");
+    expect(html).toContain("bash");
+    expect(html).toContain("2");
+  });
+
+  it("tool_call without progress events has no badge", async () => {
+    const toolMsg = makeMessage({
+      uuid: "tc-no-prog",
+      category: "tool_call",
+      content: "",
+      toolName: "Read",
+      toolUseId: "tu-no-prog",
+    });
+    const html = await generateExportHtml(makeExportRequest([toolMsg]));
+    // The CSS will contain .progress-badge as a selector, but the message HTML should not
+    // have an actual progress-badge div element
+    expect(html).not.toContain('<div class="progress-badge">');
+  });
+
+  it("print CSS forces content visible", async () => {
+    const msg = makeMessage({ uuid: "msg-print", content: "Hello" });
+    const html = await generateExportHtml(makeExportRequest([msg]));
+    expect(html).toContain("@media print");
+    // Should override collapsed hidden state for print
+    expect(html).toMatch(/\.message-body\s*\{[^}]*display:\s*block/);
+  });
 });
diff --git a/tests/unit/progress-grouper.test.ts b/tests/unit/progress-grouper.test.ts
new file mode 100644
index 0000000..004b033
--- /dev/null
+++ b/tests/unit/progress-grouper.test.ts
@@ -0,0 +1,98 @@
+import { describe, it, expect } from "vitest";
+import { groupProgress } from "../../src/server/services/progress-grouper.js";
+import type { ParsedMessage } from "../../src/shared/types.js";
+
+function makeMsg(
+  overrides: Partial<ParsedMessage> & { uuid: string; rawIndex: number }
+): ParsedMessage {
+  return {
+    category: "assistant_text",
+    content: "test",
+    ...overrides,
+  };
+}
+
+describe("progress-grouper", () => {
+  it("partitions parented progress into toolProgress map", () => {
+    const messages: ParsedMessage[] = [
+      makeMsg({ uuid: "tc-1", rawIndex: 0, category: "tool_call", toolUseId: "toolu_1" }),
+      makeMsg({ uuid: "hp-1", rawIndex: 1, category: "hook_progress", parentToolUseId: "toolu_1", progressSubtype: "hook" }),
+      makeMsg({ uuid: "hp-2", rawIndex: 2, category: "hook_progress", parentToolUseId: "toolu_1", progressSubtype: "bash" }),
+      makeMsg({ uuid: "txt-1", rawIndex: 3, category: "assistant_text" }),
+    ];
+
+    const result = groupProgress(messages);
+    expect(result.toolProgress["toolu_1"]).toHaveLength(2);
+    expect(result.toolProgress["toolu_1"][0].uuid).toBe("hp-1");
+    expect(result.toolProgress["toolu_1"][1].uuid).toBe("hp-2");
+  });
+
+  it("removes parented progress from messages array", () => {
+    const messages: ParsedMessage[] = [
+      makeMsg({ uuid: "tc-1", rawIndex: 0, category: "tool_call", toolUseId: "toolu_1" }),
+      makeMsg({ uuid: "hp-1", rawIndex: 1, category: "hook_progress", parentToolUseId: "toolu_1" }),
+      makeMsg({ uuid: "txt-1", rawIndex: 2, category: "assistant_text" }),
+    ];
+
+    const result = groupProgress(messages);
+    expect(result.messages).toHaveLength(2);
+    expect(result.messages.map((m) => m.uuid)).toEqual(["tc-1", "txt-1"]);
+  });
+
+  it("keeps orphaned progress (no parentToolUseId) in messages", () => {
+    const messages: ParsedMessage[] = [
+      makeMsg({ uuid: "hp-orphan", rawIndex: 0, category: "hook_progress", progressSubtype: "hook" }),
+      makeMsg({ uuid: "txt-1", rawIndex: 1, category: "assistant_text" }),
+    ];
+
+    const result = groupProgress(messages);
+    expect(result.messages).toHaveLength(2);
+    expect(result.messages[0].uuid).toBe("hp-orphan");
+    expect(Object.keys(result.toolProgress)).toHaveLength(0);
+  });
+
+  it("keeps progress with invalid parentToolUseId (no matching tool_call) in messages", () => {
+    const messages: ParsedMessage[] = [
+      makeMsg({ uuid: "hp-invalid", rawIndex: 0, category: "hook_progress", parentToolUseId: "toolu_nonexistent" }),
+      makeMsg({ uuid: "txt-1", rawIndex: 1, category: "assistant_text" }),
+    ];
+
+    const result = groupProgress(messages);
+    expect(result.messages).toHaveLength(2);
+    expect(result.messages[0].uuid).toBe("hp-invalid");
+  });
+
+  it("returns empty results for empty input", () => {
+    const result = groupProgress([]);
+    expect(result.messages).toEqual([]);
+    expect(result.toolProgress).toEqual({});
+  });
+
+  it("sorts each toolProgress group by rawIndex", () => {
+    const messages: ParsedMessage[] = [
+      makeMsg({ uuid: "tc-1", rawIndex: 0, category: "tool_call", toolUseId: "toolu_1" }),
+      makeMsg({ uuid: "hp-3", rawIndex: 5, category: "hook_progress", parentToolUseId: "toolu_1" }),
+      makeMsg({ uuid: "hp-1", rawIndex: 1, category: "hook_progress", parentToolUseId: "toolu_1" }),
+      makeMsg({ uuid: "hp-2", rawIndex: 3, category: "hook_progress", parentToolUseId: "toolu_1" }),
+    ];
+
+    const result = groupProgress(messages);
+    const group = result.toolProgress["toolu_1"];
+    expect(group.map((m) => m.rawIndex)).toEqual([1, 3, 5]);
+  });
+
+  it("handles multiple tool_call parents independently", () => {
+    const messages: ParsedMessage[] = [
+      makeMsg({ uuid: "tc-1", rawIndex: 0, category: "tool_call", toolUseId: "toolu_1" }),
+      makeMsg({ uuid: "hp-1a", rawIndex: 1, category: "hook_progress", parentToolUseId: "toolu_1" }),
+      makeMsg({ uuid: "tc-2", rawIndex: 2, category: "tool_call", toolUseId: "toolu_2" }),
+      makeMsg({ uuid: "hp-2a", rawIndex: 3, category: "hook_progress", parentToolUseId: "toolu_2" }),
+      makeMsg({ uuid: "hp-2b", rawIndex: 4, category: "hook_progress", parentToolUseId: "toolu_2" }),
+    ];
+
+    const result = groupProgress(messages);
+    expect(result.toolProgress["toolu_1"]).toHaveLength(1);
+    expect(result.toolProgress["toolu_2"]).toHaveLength(2);
+    expect(result.messages).toHaveLength(2); // only the 2 tool_calls
+  });
+});
diff --git a/tests/unit/session-parser.test.ts b/tests/unit/session-parser.test.ts
index 2876f00..ab6114a 100644
--- a/tests/unit/session-parser.test.ts
+++ b/tests/unit/session-parser.test.ts
@@ -216,4 +216,107 @@ describe("session-parser", () => {
     expect(msgs[0].category).toBe("user_message");
     expect(msgs[1].category).toBe("assistant_text");
   });
+
+  it("extracts toolUseId from tool_use blocks with id field", () => {
+    const line = JSON.stringify({
+      type: "assistant",
+      message: {
+        role: "assistant",
+        content: [
+          { type: "tool_use", id: "toolu_abc123", name: "Read", input: { file_path: "/src/index.ts" } },
+        ],
+      },
+      uuid: "a-tu-1",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs).toHaveLength(1);
+    expect(msgs[0].category).toBe("tool_call");
+    expect(msgs[0].toolUseId).toBe("toolu_abc123");
+  });
+
+  it("toolUseId is undefined when tool_use block has no id field", () => {
+    const line = JSON.stringify({
+      type: "assistant",
+      message: {
+        role: "assistant",
+        content: [
+          { type: "tool_use", name: "Read", input: { file_path: "/src/index.ts" } },
+        ],
+      },
+      uuid: "a-tu-2",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs).toHaveLength(1);
+    expect(msgs[0].toolUseId).toBeUndefined();
+  });
+
+  it("extracts parentToolUseId and progressSubtype from hook_progress", () => {
+    const line = JSON.stringify({
+      type: "progress",
+      data: { type: "hook_progress", hookEvent: "PreToolUse", hookName: "check" },
+      parentToolUseID: "toolu_abc123",
+      uuid: "p-linked",
+      timestamp: "2025-10-15T10:00:00Z",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs).toHaveLength(1);
+    expect(msgs[0].category).toBe("hook_progress");
+    expect(msgs[0].parentToolUseId).toBe("toolu_abc123");
+    expect(msgs[0].progressSubtype).toBe("hook");
+  });
+
+  it("derives progressSubtype 'bash' from bash_progress data type", () => {
+    const line = JSON.stringify({
+      type: "progress",
+      data: { type: "bash_progress", status: "running" },
+      parentToolUseID: "toolu_bash1",
+      uuid: "p-bash",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs[0].progressSubtype).toBe("bash");
+    expect(msgs[0].parentToolUseId).toBe("toolu_bash1");
+  });
+
+  it("derives progressSubtype 'mcp' from mcp_progress data type", () => {
+    const line = JSON.stringify({
+      type: "progress",
+      data: { type: "mcp_progress", serverName: "morph-mcp" },
+      parentToolUseID: "toolu_mcp1",
+      uuid: "p-mcp",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs[0].progressSubtype).toBe("mcp");
+  });
+
+  it("derives progressSubtype 'agent' from agent_progress data type", () => {
+    const line = JSON.stringify({
+      type: "progress",
+      data: { type: "agent_progress", status: "started" },
+      parentToolUseID: "toolu_agent1",
+      uuid: "p-agent",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs[0].progressSubtype).toBe("agent");
+  });
+
+  it("parentToolUseId is undefined when progress has no parentToolUseID", () => {
+    const line = JSON.stringify({
+      type: "progress",
+      data: { type: "hook_progress", hookEvent: "SessionStart" },
+      uuid: "p-orphan",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs[0].parentToolUseId).toBeUndefined();
+    expect(msgs[0].progressSubtype).toBe("hook");
+  });
+
+  it("progressSubtype defaults to 'hook' for unknown data types", () => {
+    const line = JSON.stringify({
+      type: "progress",
+      data: { type: "unknown_thing", status: "ok" },
+      uuid: "p-unknown",
+    });
+    const msgs = parseSessionContent(line);
+    expect(msgs[0].progressSubtype).toBe("hook");
+  });
 });