feat(cli): extend run command with port, attach, session-id, on-complete, and json options

Implement all 5 CLI extension options for external orchestration:

- --port <port>: Start server on port, or attach if port occupied
- --attach <url>: Connect to existing opencode server
- --session-id <id>: Resume existing session instead of creating new
- --on-complete <command>: Execute shell command with env vars on completion
- --json: Output structured RunResult JSON to stdout

Refactor runner.ts into focused modules:
- agent-resolver.ts: Agent resolution logic
- server-connection.ts: Server connection management
- session-resolver.ts: Session create/resume with retry
- json-output.ts: Stdout redirect + JSON emission
- on-complete-hook.ts: Shell command execution with env vars

Fixes #1586

src/cli/run/session-resolver.test.ts

@@ -0,0 +1,140 @@
+import { describe, it, expect, beforeEach, mock, spyOn } from "bun:test"
+import { resolveSession } from "./session-resolver"
+import type { OpencodeClient } from "./types"
+
+const createMockClient = (overrides: {
+  getResult?: { error?: unknown; data?: { id: string } }
+  createResults?: Array<{ error?: unknown; data?: { id: string } }>
+} = {}): OpencodeClient => {
+  const { getResult, createResults = [] } = overrides
+  let createCallIndex = 0
+  return {
+    session: {
+      get: mock((opts: { path: { id: string } }) =>
+        Promise.resolve(getResult ?? { data: { id: opts.path.id } })
+      ),
+      create: mock(() => {
+        const result =
+          createResults[createCallIndex] ?? { data: { id: "new-session-id" } }
+        createCallIndex++
+        return Promise.resolve(result)
+      }),
+    },
+  } as unknown as OpencodeClient
+}
+
+describe("resolveSession", () => {
+  beforeEach(() => {
+    spyOn(console, "log").mockImplementation(() => {})
+    spyOn(console, "error").mockImplementation(() => {})
+  })
+
+  it("returns provided session ID when session exists", async () => {
+    // given
+    const sessionId = "existing-session-id"
+    const mockClient = createMockClient({
+      getResult: { data: { id: sessionId } },
+    })
+
+    // when
+    const result = await resolveSession({ client: mockClient, sessionId })
+
+    // then
+    expect(result).toBe(sessionId)
+    expect(mockClient.session.get).toHaveBeenCalledWith({
+      path: { id: sessionId },
+    })
+    expect(mockClient.session.create).not.toHaveBeenCalled()
+  })
+
+  it("throws error when provided session ID not found", async () => {
+    // given
+    const sessionId = "non-existent-session-id"
+    const mockClient = createMockClient({
+      getResult: { error: { message: "Session not found" } },
+    })
+
+    // when
+    const result = resolveSession({ client: mockClient, sessionId })
+
+    // then
+    await expect(result).rejects.toThrow(`Session not found: ${sessionId}`)
+    expect(mockClient.session.get).toHaveBeenCalledWith({
+      path: { id: sessionId },
+    })
+    expect(mockClient.session.create).not.toHaveBeenCalled()
+  })
+
+  it("creates new session when no session ID provided", async () => {
+    // given
+    const mockClient = createMockClient({
+      createResults: [{ data: { id: "new-session-id" } }],
+    })
+
+    // when
+    const result = await resolveSession({ client: mockClient })
+
+    // then
+    expect(result).toBe("new-session-id")
+    expect(mockClient.session.create).toHaveBeenCalledWith({
+      body: { title: "oh-my-opencode run" },
+    })
+    expect(mockClient.session.get).not.toHaveBeenCalled()
+  })
+
+  it("retries session creation on failure", async () => {
+    // given
+    const mockClient = createMockClient({
+      createResults: [
+        { error: { message: "Network error" } },
+        { data: { id: "retried-session-id" } },
+      ],
+    })
+
+    // when
+    const result = await resolveSession({ client: mockClient })
+
+    // then
+    expect(result).toBe("retried-session-id")
+    expect(mockClient.session.create).toHaveBeenCalledTimes(2)
+    expect(mockClient.session.create).toHaveBeenCalledWith({
+      body: { title: "oh-my-opencode run" },
+    })
+  })
+
+  it("throws after all retries exhausted", async () => {
+    // given
+    const mockClient = createMockClient({
+      createResults: [
+        { error: { message: "Error 1" } },
+        { error: { message: "Error 2" } },
+        { error: { message: "Error 3" } },
+      ],
+    })
+
+    // when
+    const result = resolveSession({ client: mockClient })
+
+    // then
+    await expect(result).rejects.toThrow("Failed to create session after all retries")
+    expect(mockClient.session.create).toHaveBeenCalledTimes(3)
+  })
+
+  it("session creation returns no ID", async () => {
+    // given
+    const mockClient = createMockClient({
+      createResults: [
+        { data: undefined },
+        { data: undefined },
+        { data: undefined },
+      ],
+    })
+
+    // when
+    const result = resolveSession({ client: mockClient })
+
+    // then
+    await expect(result).rejects.toThrow("Failed to create session after all retries")
+    expect(mockClient.session.create).toHaveBeenCalledTimes(3)
+  })
+})