feat: integrate Pi backend and Pi Web

2026-10-03 11:09:34 +00:00 · 2026-07-30 19:37:53 +08:00
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+# Subagent Example
+
+Delegate tasks to specialized subagents with isolated context windows.
+
+## Features
+
+- **Isolated context**: Each subagent runs in a separate `pi` process
+- **Streaming output**: See tool calls and progress as they happen
+- **Parallel streaming**: All parallel tasks stream updates simultaneously
+- **Markdown rendering**: Final output rendered with proper formatting (expanded view)
+- **Usage tracking**: Shows turns, tokens, cost, and context usage per agent
+- **Abort support**: Ctrl+C propagates to kill subagent processes
+
+## Structure
+
+```
+subagent/
+├── README.md            # This file
+├── index.ts             # The extension (entry point)
+├── agents.ts            # Agent discovery logic
+├── agents/              # Sample agent definitions
+│   ├── scout.md         # Fast recon, returns compressed context
+│   ├── planner.md       # Creates implementation plans
+│   ├── reviewer.md      # Code review
+│   └── worker.md        # General-purpose (full capabilities)
+└── prompts/             # Workflow presets (prompt templates)
+    ├── implement.md     # scout -> planner -> worker
+    ├── scout-and-plan.md    # scout -> planner (no implementation)
+    └── implement-and-review.md  # worker -> reviewer -> worker
+```
+
+## Installation
+
+From the repository root, symlink the files:
+
+```bash
+# Symlink the extension (must be in a subdirectory with index.ts)
+mkdir -p ~/.pi/agent/extensions/subagent
+ln -sf "$(pwd)/packages/coding-agent/examples/extensions/subagent/index.ts" ~/.pi/agent/extensions/subagent/index.ts
+ln -sf "$(pwd)/packages/coding-agent/examples/extensions/subagent/agents.ts" ~/.pi/agent/extensions/subagent/agents.ts
+
+# Symlink agents
+mkdir -p ~/.pi/agent/agents
+for f in packages/coding-agent/examples/extensions/subagent/agents/*.md; do
+  ln -sf "$(pwd)/$f" ~/.pi/agent/agents/$(basename "$f")
+done
+
+# Symlink workflow prompts
+mkdir -p ~/.pi/agent/prompts
+for f in packages/coding-agent/examples/extensions/subagent/prompts/*.md; do
+  ln -sf "$(pwd)/$f" ~/.pi/agent/prompts/$(basename "$f")
+done
+```
+
+## Security Model
+
+This tool executes a separate `pi` subprocess with a delegated system prompt and tool/model configuration.
+
+**Project-local agents** (`.pi/agents/*.md`) are repo-controlled prompts that can instruct the model to read files, run bash commands, etc.
+
+**Default behavior:** Only loads **user-level agents** from `~/.pi/agent/agents`.
+
+To enable project-local agents, pass `agentScope: "both"` (or `"project"`). Only do this for repositories you trust.
+
+When running interactively, the tool prompts for confirmation before running project-local agents. Set `confirmProjectAgents: false` to disable.
+
+## Usage
+
+### Single agent
+```
+Use scout to find all authentication code
+```
+
+### Parallel execution
+```
+Run 2 scouts in parallel: one to find models, one to find providers
+```
+
+### Chained workflow
+```
+Use a chain: first have scout find the read tool, then have planner suggest improvements
+```
+
+### Workflow prompts
+```
+/implement add Redis caching to the session store
+/scout-and-plan refactor auth to support OAuth
+/implement-and-review add input validation to API endpoints
+```
+
+## Tool Modes
+
+| Mode | Parameter | Description |
+|------|-----------|-------------|
+| Single | `{ agent, task }` | One agent, one task |
+| Parallel | `{ tasks: [...] }` | Multiple agents run concurrently (max 8, 4 concurrent) |
+| Chain | `{ chain: [...] }` | Sequential with `{previous}` placeholder |
+
+## Output Display
+
+**Collapsed view** (default):
+- Status icon (✓/✗/⏳) and agent name
+- Last 5-10 items (tool calls and text)
+- Usage stats: `3 turns ↑input ↓output RcacheRead WcacheWrite $cost ctx:contextTokens model`
+
+**Expanded view** (Ctrl+O):
+- Full task text
+- All tool calls with formatted arguments
+- Final output rendered as Markdown
+- Per-task usage (for chain/parallel)
+
+**Parallel mode streaming**:
+- Shows all tasks with live status (⏳ running, ✓ done, ✗ failed)
+- Updates as each task makes progress
+- Shows "2/3 done, 1 running" status
+- Returns each completed task's final output to the parent model, capped at 50 KB per task
+- Returns failure diagnostics from stderr/error messages when a child exits before producing output
+
+**Tool call formatting** (mimics built-in tools):
+- `$ command` for bash
+- `read ~/path:1-10` for read
+- `grep /pattern/ in ~/path` for grep
+- etc.
+
+## Agent Definitions
+
+Agents are markdown files with YAML frontmatter:
+
+```markdown
+---
+name: my-agent
+description: What this agent does
+tools: read, grep, find, ls
+model: claude-haiku-4-5
+---
+
+System prompt for the agent goes here.
+```
+
+**Locations:**
+- `~/.pi/agent/agents/*.md` - User-level (always loaded)
+- `.pi/agents/*.md` - Project-level (only with `agentScope: "project"` or `"both"`)
+
+Project agents override user agents with the same name when `agentScope: "both"`.
+
+## Sample Agents
+
+| Agent | Purpose | Model | Tools |
+|-------|---------|-------|-------|
+| `scout` | Fast codebase recon | Haiku | read, grep, find, ls, bash |
+| `planner` | Implementation plans | Sonnet | read, grep, find, ls |
+| `reviewer` | Code review | Sonnet | read, grep, find, ls, bash |
+| `worker` | General-purpose | Sonnet | (all default) |
+
+## Workflow Prompts
+
+| Prompt | Flow |
+|--------|------|
+| `/implement <query>` | scout → planner → worker |
+| `/scout-and-plan <query>` | scout → planner |
+| `/implement-and-review <query>` | worker → reviewer → worker |
+
+## Error Handling
+
+- **Exit code != 0**: Tool returns error with stderr/output
+- **stopReason "error"**: LLM error propagated with error message
+- **stopReason "aborted"**: User abort (Ctrl+C) kills subprocess, throws error
+- **Chain mode**: Stops at first failing step, reports which step failed
+
+## Limitations
+
+- Output truncated to last 10 items in collapsed view (expand to see all)
+- Parallel model-visible output is capped at 50 KB per task; full results remain in tool details
+- Agents discovered fresh on each invocation (allows editing mid-session)
+- Parallel mode limited to 8 tasks, 4 concurrent
@@ -0,0 +1,126 @@
+/**
+ * Agent discovery and configuration
+ */
+
+import * as fs from "node:fs";
+import * as path from "node:path";
+import { CONFIG_DIR_NAME, getAgentDir, parseFrontmatter } from "@earendil-works/pi-coding-agent";
+
+export type AgentScope = "user" | "project" | "both";
+
+export interface AgentConfig {
+	name: string;
+	description: string;
+	tools?: string[];
+	model?: string;
+	systemPrompt: string;
+	source: "user" | "project";
+	filePath: string;
+}
+
+export interface AgentDiscoveryResult {
+	agents: AgentConfig[];
+	projectAgentsDir: string | null;
+}
+
+function loadAgentsFromDir(dir: string, source: "user" | "project"): AgentConfig[] {
+	const agents: AgentConfig[] = [];
+
+	if (!fs.existsSync(dir)) {
+		return agents;
+	}
+
+	let entries: fs.Dirent[];
+	try {
+		entries = fs.readdirSync(dir, { withFileTypes: true });
+	} catch {
+		return agents;
+	}
+
+	for (const entry of entries) {
+		if (!entry.name.endsWith(".md")) continue;
+		if (!entry.isFile() && !entry.isSymbolicLink()) continue;
+
+		const filePath = path.join(dir, entry.name);
+		let content: string;
+		try {
+			content = fs.readFileSync(filePath, "utf-8");
+		} catch {
+			continue;
+		}
+
+		const { frontmatter, body } = parseFrontmatter<Record<string, string>>(content);
+
+		if (!frontmatter.name || !frontmatter.description) {
+			continue;
+		}
+
+		const tools = frontmatter.tools
+			?.split(",")
+			.map((t: string) => t.trim())
+			.filter(Boolean);
+
+		agents.push({
+			name: frontmatter.name,
+			description: frontmatter.description,
+			tools: tools && tools.length > 0 ? tools : undefined,
+			model: frontmatter.model,
+			systemPrompt: body,
+			source,
+			filePath,
+		});
+	}
+
+	return agents;
+}
+
+function isDirectory(p: string): boolean {
+	try {
+		return fs.statSync(p).isDirectory();
+	} catch {
+		return false;
+	}
+}
+
+function findNearestProjectAgentsDir(cwd: string): string | null {
+	let currentDir = cwd;
+	while (true) {
+		const candidate = path.join(currentDir, CONFIG_DIR_NAME, "agents");
+		if (isDirectory(candidate)) return candidate;
+
+		const parentDir = path.dirname(currentDir);
+		if (parentDir === currentDir) return null;
+		currentDir = parentDir;
+	}
+}
+
+export function discoverAgents(cwd: string, scope: AgentScope): AgentDiscoveryResult {
+	const userDir = path.join(getAgentDir(), "agents");
+	const projectAgentsDir = findNearestProjectAgentsDir(cwd);
+
+	const userAgents = scope === "project" ? [] : loadAgentsFromDir(userDir, "user");
+	const projectAgents = scope === "user" || !projectAgentsDir ? [] : loadAgentsFromDir(projectAgentsDir, "project");
+
+	const agentMap = new Map<string, AgentConfig>();
+
+	if (scope === "both") {
+		for (const agent of userAgents) agentMap.set(agent.name, agent);
+		for (const agent of projectAgents) agentMap.set(agent.name, agent);
+	} else if (scope === "user") {
+		for (const agent of userAgents) agentMap.set(agent.name, agent);
+	} else {
+		for (const agent of projectAgents) agentMap.set(agent.name, agent);
+	}
+
+	return { agents: Array.from(agentMap.values()), projectAgentsDir };
+}
+
+export function formatAgentList(agents: AgentConfig[], maxItems: number): { text: string; remaining: number } {
+	if (agents.length === 0) return { text: "none", remaining: 0 };
+	const listed = agents.slice(0, maxItems);
+	const remaining = agents.length - listed.length;
+	return {
+		text: listed.map((a) => `${a.name} (${a.source}): ${a.description}`).join("; "),
+		remaining,
+	};
+}
@@ -0,0 +1,37 @@
+---
+name: planner
+description: Creates implementation plans from context and requirements
+tools: read, grep, find, ls
+model: claude-sonnet-4-5
+---
+
+You are a planning specialist. You receive context (from a scout) and requirements, then produce a clear implementation plan.
+
+You must NOT make any changes. Only read, analyze, and plan.
+
+Input format you'll receive:
+- Context/findings from a scout agent
+- Original query or requirements
+
+Output format:
+
+## Goal
+One sentence summary of what needs to be done.
+
+## Plan
+Numbered steps, each small and actionable:
+1. Step one - specific file/function to modify
+2. Step two - what to add/change
+3. ...
+
+## Files to Modify
+- `path/to/file.ts` - what changes
+- `path/to/other.ts` - what changes
+
+## New Files (if any)
+- `path/to/new.ts` - purpose
+
+## Risks
+Anything to watch out for.
+
+Keep the plan concrete. The worker agent will execute it verbatim.
@@ -0,0 +1,35 @@
+---
+name: reviewer
+description: Code review specialist for quality and security analysis
+tools: read, grep, find, ls, bash
+model: claude-sonnet-4-5
+---
+
+You are a senior code reviewer. Analyze code for quality, security, and maintainability.
+
+Bash is for read-only commands only: `git diff`, `git log`, `git show`. Do NOT modify files or run builds.
+Assume tool permissions are not perfectly enforceable; keep all bash usage strictly read-only.
+
+Strategy:
+1. Run `git diff` to see recent changes (if applicable)
+2. Read the modified files
+3. Check for bugs, security issues, code smells
+
+Output format:
+
+## Files Reviewed
+- `path/to/file.ts` (lines X-Y)
+
+## Critical (must fix)
+- `file.ts:42` - Issue description
+
+## Warnings (should fix)
+- `file.ts:100` - Issue description
+
+## Suggestions (consider)
+- `file.ts:150` - Improvement idea
+
+## Summary
+Overall assessment in 2-3 sentences.
+
+Be specific with file paths and line numbers.
@@ -0,0 +1,50 @@
+---
+name: scout
+description: Fast codebase recon that returns compressed context for handoff to other agents
+tools: read, grep, find, ls, bash
+model: claude-haiku-4-5
+---
+
+You are a scout. Quickly investigate a codebase and return structured findings that another agent can use without re-reading everything.
+
+Your output will be passed to an agent who has NOT seen the files you explored.
+
+Thoroughness (infer from task, default medium):
+- Quick: Targeted lookups, key files only
+- Medium: Follow imports, read critical sections
+- Thorough: Trace all dependencies, check tests/types
+
+Strategy:
+1. grep/find to locate relevant code
+2. Read key sections (not entire files)
+3. Identify types, interfaces, key functions
+4. Note dependencies between files
+
+Output format:
+
+## Files Retrieved
+List with exact line ranges:
+1. `path/to/file.ts` (lines 10-50) - Description of what's here
+2. `path/to/other.ts` (lines 100-150) - Description
+3. ...
+
+## Key Code
+Critical types, interfaces, or functions:
+
+```typescript
+interface Example {
+  // actual code from the files
+}
+```
+
+```typescript
+function keyFunction() {
+  // actual implementation
+}
+```
+
+## Architecture
+Brief explanation of how the pieces connect.
+
+## Start Here
+Which file to look at first and why.
@@ -0,0 +1,24 @@
+---
+name: worker
+description: General-purpose subagent with full capabilities, isolated context
+model: claude-sonnet-4-5
+---
+
+You are a worker agent with full capabilities. You operate in an isolated context window to handle delegated tasks without polluting the main conversation.
+
+Work autonomously to complete the assigned task. Use all available tools as needed.
+
+Output format when finished:
+
+## Completed
+What was done.
+
+## Files Changed
+- `path/to/file.ts` - what changed
+
+## Notes (if any)
+Anything the main agent should know.
+
+If handing off to another agent (e.g. reviewer), include:
+- Exact file paths changed
+- Key functions/types touched (short list)
@@ -0,0 +1,10 @@
+---
+description: Worker implements, reviewer reviews, worker applies feedback
+---
+Use the subagent tool with the chain parameter to execute this workflow:
+
+1. First, use the "worker" agent to implement: $@
+2. Then, use the "reviewer" agent to review the implementation from the previous step (use {previous} placeholder)
+3. Finally, use the "worker" agent to apply the feedback from the review (use {previous} placeholder)
+
+Execute this as a chain, passing output between steps via {previous}.
@@ -0,0 +1,10 @@
+---
+description: Full implementation workflow - scout gathers context, planner creates plan, worker implements
+---
+Use the subagent tool with the chain parameter to execute this workflow:
+
+1. First, use the "scout" agent to find all code relevant to: $@
+2. Then, use the "planner" agent to create an implementation plan for "$@" using the context from the previous step (use {previous} placeholder)
+3. Finally, use the "worker" agent to implement the plan from the previous step (use {previous} placeholder)
+
+Execute this as a chain, passing output between steps via {previous}.
@@ -0,0 +1,9 @@
+---
+description: Scout gathers context, planner creates implementation plan (no implementation)
+---
+Use the subagent tool with the chain parameter to execute this workflow:
+
+1. First, use the "scout" agent to find all code relevant to: $@
+2. Then, use the "planner" agent to create an implementation plan for "$@" using the context from the previous step (use {previous} placeholder)
+
+Execute this as a chain, passing output between steps via {previous}. Do NOT implement - just return the plan.