feat(cli): add agent send command

Implements the `agent send` command for sending messages to existing agents.

Features:
- Send follow-up tasks to running agents
- Support for ID prefix matching (e.g., "a1b2" matches "a1b2c3d4")
- --no-wait flag to return immediately without waiting for completion
- Default behavior waits for agent to become idle

Usage:
  paseo agent send <id> <prompt>
  paseo agent send --no-wait a1b2c3d "Run the linter"

packages/cli/src/commands/agent/index.ts

@@ -2,6 +2,7 @@ import { Command } from 'commander'
 import { runPsCommand } from './ps.js'
 import { runRunCommand } from './run.js'
 import { runSendCommand } from './send.js'
+import { runStopCommand } from './stop.js'
 import { withOutput } from '../../output/index.js'
 
 export function createAgentCommand(): Command {
@@ -37,5 +38,14 @@ export function createAgentCommand(): Command {
     .option('--host <host>', 'Daemon host:port (default: localhost:6767)')
     .action(withOutput(runSendCommand))
 
+  agent
+    .command('stop')
+    .description('Stop an agent (cancel if running, then terminate)')
+    .argument('[id]', 'Agent ID (or prefix) - optional if --all or --cwd specified')
+    .option('--all', 'Stop all agents')
+    .option('--cwd <path>', 'Stop all agents in directory')
+    .option('--host <host>', 'Daemon host:port (default: localhost:6767)')
+    .action(withOutput(runStopCommand))
+
   return agent
 }

packages/cli/src/commands/agent/send.ts

@@ -0,0 +1,164 @@
+import type { Command } from 'commander'
+import { connectToDaemon, getDaemonHost } from '../../utils/client.js'
+import type { CommandOptions, SingleResult, OutputSchema, CommandError } from '../../output/index.js'
+
+/** Minimal agent snapshot type (from daemon client) */
+interface AgentSnapshot {
+  id: string
+  provider: string
+  cwd: string
+  createdAt: string
+  status: string
+  title: string | null
+}
+
+/** Result type for agent send command */
+export interface AgentSendResult {
+  agentId: string
+  status: 'sent' | 'completed'
+  message: string
+}
+
+/** Schema for agent send output */
+export const agentSendSchema: OutputSchema<AgentSendResult> = {
+  idField: 'agentId',
+  columns: [
+    { header: 'AGENT ID', field: 'agentId', width: 12 },
+    { header: 'STATUS', field: 'status', width: 12 },
+    { header: 'MESSAGE', field: 'message', width: 40 },
+  ],
+}
+
+export interface AgentSendOptions extends CommandOptions {
+  noWait?: boolean
+}
+
+/**
+ * Resolve agent ID from prefix or full ID.
+ * Supports exact match and prefix matching.
+ */
+function resolveAgentId(agents: AgentSnapshot[], idOrPrefix: string): string | null {
+  // Exact match first
+  const exact = agents.find((a) => a.id === idOrPrefix)
+  if (exact) return exact.id
+
+  // Prefix match
+  const matches = agents.filter((a) => a.id.startsWith(idOrPrefix))
+  if (matches.length === 1 && matches[0]) return matches[0].id
+  if (matches.length > 1) {
+    throw new Error(
+      `Ambiguous ID prefix '${idOrPrefix}': matches ${matches.length} agents (${matches.map((a) => a.id.slice(0, 7)).join(', ')})`
+    )
+  }
+
+  return null
+}
+
+export async function runSendCommand(
+  agentIdArg: string,
+  prompt: string,
+  options: AgentSendOptions,
+  _command: Command
+): Promise<SingleResult<AgentSendResult>> {
+  const host = getDaemonHost({ host: options.host as string | undefined })
+
+  // Validate arguments
+  if (!agentIdArg || agentIdArg.trim().length === 0) {
+    const error: CommandError = {
+      code: 'MISSING_AGENT_ID',
+      message: 'Agent ID is required',
+      details: 'Usage: paseo agent send [options] <id> <prompt>',
+    }
+    throw error
+  }
+
+  if (!prompt || prompt.trim().length === 0) {
+    const error: CommandError = {
+      code: 'MISSING_PROMPT',
+      message: 'A prompt is required',
+      details: 'Usage: paseo agent send [options] <id> <prompt>',
+    }
+    throw error
+  }
+
+  let client
+  try {
+    client = await connectToDaemon({ host: options.host as string | undefined })
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err)
+    const error: CommandError = {
+      code: 'DAEMON_NOT_RUNNING',
+      message: `Cannot connect to daemon at ${host}: ${message}`,
+      details: 'Start the daemon with: paseo daemon start',
+    }
+    throw error
+  }
+
+  try {
+    // Request session state to get agent information
+    client.requestSessionState()
+
+    // Wait a moment for the session state to be populated
+    await new Promise((resolve) => setTimeout(resolve, 500))
+
+    const agents = client.listAgents()
+
+    // Resolve agent ID (supports prefix matching)
+    const agentId = resolveAgentId(agents, agentIdArg)
+    if (!agentId) {
+      const error: CommandError = {
+        code: 'AGENT_NOT_FOUND',
+        message: `Agent not found: ${agentIdArg}`,
+        details: 'Use "paseo agent ps" to list available agents',
+      }
+      throw error
+    }
+
+    // Send the message
+    await client.sendAgentMessage(agentId, prompt)
+
+    // If --no-wait, return immediately
+    if (options.noWait) {
+      await client.close()
+
+      return {
+        type: 'single',
+        data: {
+          agentId,
+          status: 'sent',
+          message: 'Message sent, not waiting for completion',
+        },
+        schema: agentSendSchema,
+      }
+    }
+
+    // Wait for agent to become idle
+    await client.waitForAgentIdle(agentId, 600000) // 10 minute timeout
+
+    await client.close()
+
+    return {
+      type: 'single',
+      data: {
+        agentId,
+        status: 'completed',
+        message: 'Agent completed processing the message',
+      },
+      schema: agentSendSchema,
+    }
+  } catch (err) {
+    await client.close().catch(() => {})
+
+    // Re-throw CommandError as-is
+    if (err && typeof err === 'object' && 'code' in err) {
+      throw err
+    }
+
+    const message = err instanceof Error ? err.message : String(err)
+    const error: CommandError = {
+      code: 'SEND_FAILED',
+      message: `Failed to send message: ${message}`,
+    }
+    throw error
+  }
+}