feat(commands): add start-work command

Add /start-work command for executing Prometheus plans:
- start-work.ts: Command template for orchestrator-sisyphus
- commands.ts: Register command with agent binding
- types.ts: Add command name to type union

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/features/builtin-commands/commands.ts

@@ -3,6 +3,7 @@ import type { BuiltinCommandName, BuiltinCommands } from "./types"
 import { INIT_DEEP_TEMPLATE } from "./templates/init-deep"
 import { RALPH_LOOP_TEMPLATE, CANCEL_RALPH_TEMPLATE } from "./templates/ralph-loop"
 import { REFACTOR_TEMPLATE } from "./templates/refactor"
+import { START_WORK_TEMPLATE } from "./templates/start-work"
 
 const BUILTIN_COMMAND_DEFINITIONS: Record<BuiltinCommandName, Omit<CommandDefinition, "name">> = {
   "init-deep": {
@@ -41,6 +42,23 @@ ${REFACTOR_TEMPLATE}
 </command-instruction>`,
     argumentHint: "<refactoring-target> [--scope=<file|module|project>] [--strategy=<safe|aggressive>]",
   },
+  "start-work": {
+    description: "(builtin) Start Sisyphus work session from Prometheus plan",
+    agent: "orchestrator-sisyphus",
+    template: `<command-instruction>
+${START_WORK_TEMPLATE}
+</command-instruction>
+
+<session-context>
+Session ID: $SESSION_ID
+Timestamp: $TIMESTAMP
+</session-context>
+
+<user-request>
+$ARGUMENTS
+</user-request>`,
+    argumentHint: "[plan-name]",
+  },
 }
 
 export function loadBuiltinCommands(

src/features/builtin-commands/templates/start-work.ts

@@ -0,0 +1,72 @@
+export const START_WORK_TEMPLATE = `You are starting a Sisyphus work session.
+
+## WHAT TO DO
+
+1. **Find available plans**: Search for Prometheus-generated plan files at \`.sisyphus/plans/\`
+
+2. **Check for active boulder state**: Read \`.sisyphus/boulder.json\` if it exists
+
+3. **Decision logic**:
+   - If \`.sisyphus/boulder.json\` exists AND plan is NOT complete (has unchecked boxes):
+     - **APPEND** current session to session_ids
+     - Continue work on existing plan
+   - If no active plan OR plan is complete:
+     - List available plan files
+     - If ONE plan: auto-select it
+     - If MULTIPLE plans: show list with timestamps, ask user to select
+
+4. **Create/Update boulder.json**:
+   \`\`\`json
+   {
+     "active_plan": "/absolute/path/to/plan.md",
+     "started_at": "ISO_TIMESTAMP",
+     "session_ids": ["session_id_1", "session_id_2"],
+     "plan_name": "plan-name"
+   }
+   \`\`\`
+
+5. **Read the plan file** and start executing tasks according to Orchestrator Sisyphus workflow
+
+## OUTPUT FORMAT
+
+When listing plans for selection:
+\`\`\`
+📋 Available Work Plans
+
+Current Time: {ISO timestamp}
+Session ID: {current session id}
+
+1. [plan-name-1.md] - Modified: {date} - Progress: 3/10 tasks
+2. [plan-name-2.md] - Modified: {date} - Progress: 0/5 tasks
+
+Which plan would you like to work on? (Enter number or plan name)
+\`\`\`
+
+When resuming existing work:
+\`\`\`
+🔄 Resuming Work Session
+
+Active Plan: {plan-name}
+Progress: {completed}/{total} tasks
+Sessions: {count} (appending current session)
+
+Reading plan and continuing from last incomplete task...
+\`\`\`
+
+When auto-selecting single plan:
+\`\`\`
+🚀 Starting Work Session
+
+Plan: {plan-name}
+Session ID: {session_id}
+Started: {timestamp}
+
+Reading plan and beginning execution...
+\`\`\`
+
+## CRITICAL
+
+- The session_id is injected by the hook - use it directly
+- Always update boulder.json BEFORE starting work
+- Read the FULL plan file before delegating any tasks
+- Follow Orchestrator Sisyphus delegation protocols (7-section format)`

src/features/builtin-commands/types.ts

@@ -1,6 +1,6 @@
 import type { CommandDefinition } from "../claude-code-command-loader"
 
-export type BuiltinCommandName = "init-deep" | "ralph-loop" | "cancel-ralph" | "refactor"
+export type BuiltinCommandName = "init-deep" | "ralph-loop" | "cancel-ralph" | "refactor" | "start-work"
 
 export interface BuiltinCommandConfig {
   disabled_commands?: BuiltinCommandName[]