feat(KB-123): add agent role tracking and expanded logging to agent system

- Extend AgentLogEntry with agent field and new event types (thinking, tool_end)
- Expand AgentLogger with thinking, tool_end callbacks and agent role support
- Wire new logging callbacks in createKbAgent and all agent call-sites (executor, merger, reviewer, triage, pi)
- Update AgentLogViewer with agent role badges and rendering for new entry types
- Export AgentRole and AgentLogType from core package and add tests for new functionality

packages/core/src/index.ts

@@ -1,4 +1,4 @@
 export { COLUMNS, COLUMN_LABELS, COLUMN_DESCRIPTIONS, VALID_TRANSITIONS, DEFAULT_SETTINGS, THINKING_LEVELS } from "./types.js";
-export type { Column, Task, TaskAttachment, TaskCreateInput, TaskDetail, AgentLogEntry, BoardConfig, MergeResult, Settings, TaskStep, StepStatus, TaskLogEntry, ThinkingLevel } from "./types.js";
+export type { Column, Task, TaskAttachment, TaskCreateInput, TaskDetail, AgentLogEntry, AgentLogType, AgentRole, BoardConfig, MergeResult, Settings, TaskStep, StepStatus, TaskLogEntry, ThinkingLevel } from "./types.js";
 export { TaskStore } from "./store.js";
 export { canTransition, getValidTransitions, resolveDependencyOrder } from "./board.js";

packages/core/src/store.test.ts

@@ -610,6 +610,52 @@ describe("TaskStore", () => {
       expect(logs).toHaveLength(5);
       expect(logs[4].text).toBe("chunk 4");
     });
+
+    it("appendAgentLog persists and reads back the agent field", async () => {
+      const task = await createTestTask();
+
+      await store.appendAgentLog(task.id, "hello", "text", undefined, "executor");
+      await store.appendAgentLog(task.id, "Read", "tool", "file.ts", "triage");
+
+      const logs = await store.getAgentLogs(task.id);
+      expect(logs).toHaveLength(2);
+      expect(logs[0].agent).toBe("executor");
+      expect(logs[1].agent).toBe("triage");
+    });
+
+    it("appendAgentLog omits agent field when not provided", async () => {
+      const task = await createTestTask();
+
+      await store.appendAgentLog(task.id, "hello", "text");
+
+      const logs = await store.getAgentLogs(task.id);
+      expect(logs).toHaveLength(1);
+      expect(logs[0]).not.toHaveProperty("agent");
+    });
+
+    it("new type values (thinking, tool_result, tool_error) round-trip correctly", async () => {
+      const task = await createTestTask();
+
+      await store.appendAgentLog(task.id, "internal thought", "thinking", undefined, "executor");
+      await store.appendAgentLog(task.id, "Bash", "tool_result", "output summary", "executor");
+      await store.appendAgentLog(task.id, "Read", "tool_error", "file not found", "reviewer");
+
+      const logs = await store.getAgentLogs(task.id);
+      expect(logs).toHaveLength(3);
+
+      expect(logs[0].type).toBe("thinking");
+      expect(logs[0].text).toBe("internal thought");
+      expect(logs[0].agent).toBe("executor");
+
+      expect(logs[1].type).toBe("tool_result");
+      expect(logs[1].text).toBe("Bash");
+      expect(logs[1].detail).toBe("output summary");
+
+      expect(logs[2].type).toBe("tool_error");
+      expect(logs[2].text).toBe("Read");
+      expect(logs[2].detail).toBe("file not found");
+      expect(logs[2].agent).toBe("reviewer");
+    });
   });
 
   describe("columnMovedAt", () => {

packages/core/src/store.ts

@@ -882,17 +882,25 @@ export class TaskStore extends EventEmitter<TaskStoreEvents> {
    * Also emits an `agent:log` event for live streaming.
    *
    * @param taskId - The task ID (e.g. "KB-001")
-   * @param text - The text content (delta for "text", tool name for "tool")
-   * @param type - Whether this is a "text" delta or a "tool" invocation marker
-   * @param detail - Optional human-readable summary of tool args (e.g. file path, command)
+   * @param text - The text content (delta for "text"/"thinking", tool name for "tool"/"tool_result"/"tool_error")
+   * @param type - The entry type discriminator
+   * @param detail - Optional human-readable summary (tool args, result summary, or error message)
+   * @param agent - Optional agent role that produced this entry
    */
-  async appendAgentLog(taskId: string, text: string, type: "text" | "tool", detail?: string): Promise<void> {
+  async appendAgentLog(
+    taskId: string,
+    text: string,
+    type: AgentLogEntry["type"],
+    detail?: string,
+    agent?: AgentLogEntry["agent"],
+  ): Promise<void> {
     const entry: AgentLogEntry = {
       timestamp: new Date().toISOString(),
       taskId,
       text,
       type,
       ...(detail !== undefined && { detail }),
+      ...(agent !== undefined && { agent }),
     };
     const dir = this.taskDir(taskId);
     const logPath = join(dir, "agent.log");

packages/core/src/types.ts

@@ -18,18 +18,27 @@ export interface TaskLogEntry {
   outcome?: string;
 }
 
-/** A single chunk of agent output (text delta or tool invocation) persisted to disk. */
+/** The set of agent roles that produce log entries. */
+export type AgentRole = "triage" | "executor" | "reviewer" | "merger";
+
+/** The discriminator for agent log entry types. */
+export type AgentLogType = "text" | "tool" | "thinking" | "tool_result" | "tool_error";
+
+/** A single chunk of agent output persisted to disk (JSONL in agent.log). */
 export interface AgentLogEntry {
-  /** ISO-8601 timestamp of when the entry was recorded */
+  /** ISO-8601 timestamp of when the entry was recorded. */
   timestamp: string;
-  /** The task this log entry belongs to */
+  /** The task this log entry belongs to. */
   taskId: string;
-  /** The text content (delta for "text", tool name for "tool") */
+  /** The text content (delta for "text"/"thinking", tool name for "tool"/"tool_result"/"tool_error"). */
   text: string;
-  /** Whether this is a text delta or a tool invocation marker */
-  type: "text" | "tool";
-  /** For tool entries: human-readable summary of tool args (e.g. file path, command) */
+  /** The kind of entry — text delta, tool invocation marker, thinking block, tool result, or tool error. */
+  type: AgentLogType;
+  /** For tool entries: human-readable summary of tool args (e.g. file path, command).
+   *  For tool_result/tool_error: summary of the result or error message. */
   detail?: string;
+  /** Which agent produced this entry. Absent in logs written before this field was added. */
+  agent?: AgentRole;
 }
 
 export interface TaskAttachment {