feat(coding-agent): expose session metadata to bash tools (#6967)

packages/coding-agent/docs/extensions.md

@@ -982,9 +982,9 @@ ctx.sessionManager.buildContextEntries()    // Active branch entries with compac
 ctx.sessionManager.getLeafId()              // Current leaf entry ID
 ```
 
-### ctx.modelRegistry / ctx.model
+### ctx.modelRegistry / ctx.model / ctx.thinkingLevel
 
-Access to models, providers, and resolved authentication. `ctx.modelRegistry.getProvider(id)` returns the effective pi-ai provider, while `getProviderAuth(id)` resolves its current API key, headers, base URL, and provider-scoped environment without requiring a loaded model. `ctx.model` is the active model.
+Access to models, providers, and resolved authentication. `ctx.modelRegistry.getProvider(id)` returns the effective pi-ai provider, while `getProviderAuth(id)` resolves its current API key, headers, base URL, and provider-scoped environment without requiring a loaded model. `ctx.model` is the active model, and `ctx.thinkingLevel` is its current effective thinking level.
 
 ### ctx.signal
 
@@ -2096,7 +2096,15 @@ const bashTool = createBashTool(cwd, {
 });
 ```
 
-See [examples/extensions/ssh.ts](../examples/extensions/ssh.ts) for a complete SSH example with `--ssh` flag.
+`createBashTool()` exposes the current session to commands through `PI_SESSION_ID`, `PI_SESSION_FILE`, `PI_PROVIDER`, `PI_MODEL`, and `PI_REASONING_LEVEL`. Injection happens before `spawnHook`, so hooks receive these values in `env` and preserve them when they spread the existing environment as above. Set `exposeSessionEnvironment: false` to disable them:
+
+```typescript
+const bashTool = createBashTool(cwd, {
+  exposeSessionEnvironment: false,
+});
+```
+
+See [Bash tool session environment](environment-variables.md#bash-tool-session-environment) for variable semantics. See [examples/extensions/ssh.ts](../examples/extensions/ssh.ts) for a complete SSH example with `--ssh` flag.
 
 ### Output Truncation