codex: support hooks in config.toml and requirements.toml (#18893)

## Summary

Support the existing hooks schema in inline TOML so hooks can be
configured from both `config.toml` and enterprise-managed
`requirements.toml` without requiring a separate `hooks.json` payload.

This gives enterprise admins a way to ship managed hook policy through
the existing requirements channel while still leaving script delivery to
MDM or other device-management tooling, and it keeps `hooks.json`
working unchanged for existing users.

This also lays the groundwork for follow-on managed filtering work such
as #15937, while continuing to respect project trust gating from #14718.
It does **not** implement `allow_managed_hooks_only` itself.

NOTE: yes, it's a bit unfortunate that the toml isn't formatted as
closely as normal to our default styling. This is because we're trying
to stay compatible with the spec for plugins/hooks that we'll need to
support & the main usecase here is embedding into requirements.toml

## What changed

- moved the shared hook serde model out of `codex-rs/hooks` into
`codex-rs/config` so the same schema can power `hooks.json`, inline
`config.toml` hooks, and managed `requirements.toml` hooks
- added `hooks` support to both `ConfigToml` and
`ConfigRequirementsToml`, including requirements-side `managed_dir` /
`windows_managed_dir`
- treated requirements-managed hooks as one constrained value via
`Constrained`, so managed hook policy is merged atomically and cannot
drift across requirement sources
- updated hook discovery to load requirements-managed hooks first, then
per-layer `hooks.json`, then per-layer inline TOML hooks, with a warning
when a single layer defines both representations
- threaded managed hook metadata through discovered handlers and exposed
requirements hooks in app-server responses, generated schemas, and
`/debug-config`
- added hook/config coverage in `codex-rs/config`, `codex-rs/hooks`,
`codex-rs/core/src/config_loader/tests.rs`, and
`codex-rs/core/tests/suite/hooks.rs`

## Testing

- `cargo test -p codex-config`
- `cargo test -p codex-hooks`
- `cargo test -p codex-app-server config_api`

## Documentation

Companion updates are needed in the developers website repo for:

- the hooks guide
- the config reference, sample, basic, and advanced pages
- the enterprise managed configuration guide

---------

Co-authored-by: Michael Bolin <mbolin@openai.com>

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -941,11 +941,71 @@ pub struct ConfigRequirements {
     pub allowed_sandbox_modes: Option<Vec<SandboxMode>>,
     pub allowed_web_search_modes: Option<Vec<WebSearchMode>>,
     pub feature_requirements: Option<BTreeMap<String, bool>>,
+    #[experimental("configRequirements/read.hooks")]
+    pub hooks: Option<ManagedHooksRequirements>,
     pub enforce_residency: Option<ResidencyRequirement>,
     #[experimental("configRequirements/read.network")]
     pub network: Option<NetworkRequirements>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ManagedHooksRequirements {
+    pub managed_dir: Option<PathBuf>,
+    pub windows_managed_dir: Option<PathBuf>,
+    #[serde(rename = "PreToolUse")]
+    #[ts(rename = "PreToolUse")]
+    pub pre_tool_use: Vec<ConfiguredHookMatcherGroup>,
+    #[serde(rename = "PermissionRequest")]
+    #[ts(rename = "PermissionRequest")]
+    pub permission_request: Vec<ConfiguredHookMatcherGroup>,
+    #[serde(rename = "PostToolUse")]
+    #[ts(rename = "PostToolUse")]
+    pub post_tool_use: Vec<ConfiguredHookMatcherGroup>,
+    #[serde(rename = "SessionStart")]
+    #[ts(rename = "SessionStart")]
+    pub session_start: Vec<ConfiguredHookMatcherGroup>,
+    #[serde(rename = "UserPromptSubmit")]
+    #[ts(rename = "UserPromptSubmit")]
+    pub user_prompt_submit: Vec<ConfiguredHookMatcherGroup>,
+    #[serde(rename = "Stop")]
+    #[ts(rename = "Stop")]
+    pub stop: Vec<ConfiguredHookMatcherGroup>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ConfiguredHookMatcherGroup {
+    pub matcher: Option<String>,
+    pub hooks: Vec<ConfiguredHookHandler>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(tag = "type")]
+#[ts(tag = "type", export_to = "v2/")]
+pub enum ConfiguredHookHandler {
+    #[serde(rename = "command")]
+    #[ts(rename = "command")]
+    Command {
+        command: String,
+        #[serde(rename = "timeoutSec")]
+        #[ts(rename = "timeoutSec")]
+        timeout_sec: Option<u64>,
+        r#async: bool,
+        #[serde(rename = "statusMessage")]
+        #[ts(rename = "statusMessage")]
+        status_message: Option<String>,
+    },
+    #[serde(rename = "prompt")]
+    #[ts(rename = "prompt")]
+    Prompt {},
+    #[serde(rename = "agent")]
+    #[ts(rename = "agent")]
+    Agent {},
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
@@ -8837,6 +8897,7 @@ mod tests {
                 allowed_sandbox_modes: None,
                 allowed_web_search_modes: None,
                 feature_requirements: None,
+                hooks: None,
                 enforce_residency: None,
                 network: None,
             });