docs(hooks): add plugin-style lifecycle hook examples

README.md

@@ -1003,6 +1003,16 @@ PicoClaw routes providers by protocol family:
 
 This keeps the runtime lightweight while making new OpenAI-compatible backends mostly a config operation (`api_base` + `api_key`).
 
+### Lifecycle Hooks (Plugin-style Extensions)
+
+PicoClaw provides typed lifecycle hooks for observability, outbound filtering, and tool guardrails.
+
+- Register hooks in Go at startup with `hooks.NewHookRegistry()`.
+- Attach once via `agentLoop.SetHooks(registry)` before `Run()`.
+- If hooks are not set, default behavior is unchanged.
+
+See runnable examples: [docs/hooks-plugin-examples.md](docs/hooks-plugin-examples.md)
+
 <details>
 <summary><b>Zhipu</b></summary>
 

docs/hooks-plugin-examples.md

@@ -0,0 +1,88 @@
+# Lifecycle Hooks: Plugin-Style Examples
+
+This guide shows how to extend PicoClaw behavior with `pkg/hooks` without modifying core agent logic.
+
+Current model:
+- "Plugin-style" means registering Go handlers at startup.
+- Hooks are in-process (no dynamic `.so` loading).
+- If no hooks are registered, the runtime follows the normal zero-cost path.
+
+## Available Hooks
+
+| Hook | Type | Typical use |
+|---|---|---|
+| `message_received` | observe-only | inbound telemetry |
+| `message_sending` | modifying + cancel | content filtering, safety policy |
+| `before_tool_call` | modifying + cancel | tool allow/deny, arg rewriting |
+| `after_tool_call` | observe-only | latency/error metrics |
+| `llm_input` | observe-only | prompt size monitoring |
+| `llm_output` | observe-only | response/tool-call telemetry |
+| `session_start` | observe-only | session audit |
+| `session_end` | observe-only | session cleanup metrics |
+
+## Quick Start
+
+```go
+package main
+
+import (
+	"context"
+	"strings"
+
+	"github.com/sipeed/picoclaw/pkg/hooks"
+)
+
+func buildHooks() *hooks.HookRegistry {
+	reg := hooks.NewHookRegistry()
+
+	// 1) Guardrail: block shell tool globally.
+	reg.OnBeforeToolCall("block-shell", 100, func(_ context.Context, e *hooks.BeforeToolCallEvent) error {
+		if e.ToolName == "shell" {
+			e.Cancel = true
+			e.CancelReason = "shell tool is disabled by local policy"
+		}
+		return nil
+	})
+
+	// 2) Outbound filter: redact obvious API key patterns.
+	reg.OnMessageSending("redact-secrets", 50, func(_ context.Context, e *hooks.MessageSendingEvent) error {
+		e.Content = strings.ReplaceAll(e.Content, "sk-", "[redacted]-")
+		return nil
+	})
+
+	// 3) Telemetry: record tool latency or errors.
+	reg.OnAfterToolCall("tool-telemetry", 0, func(_ context.Context, e *hooks.AfterToolCallEvent) error {
+		// Send to metrics backend / logs as needed.
+		_ = e.ToolName
+		_ = e.Duration
+		_ = e.Result
+		return nil
+	})
+
+	return reg
+}
+```
+
+Attach once during startup:
+
+```go
+agentLoop := agent.NewAgentLoop(cfg, msgBus, provider)
+agentLoop.SetHooks(buildHooks()) // Must be called before Run()
+```
+
+## Priority and Cancellation
+
+- Lower `priority` runs first.
+- `message_sending` and `before_tool_call` are sequential and can cancel.
+- Other hooks are observe-only and run concurrently.
+
+Recommended ordering:
+- `0-49`: telemetry and logging
+- `50-89`: transforms (redaction, normalization)
+- `90+`: hard guardrails (block/cancel)
+
+## Safety Notes
+
+- Hook panics are recovered internally; one bad hook does not crash the loop.
+- Hook errors are logged and execution continues unless `Cancel` is set.
+- Keep hook handlers fast and non-blocking to avoid latency impact.