Extract tool-suggest wire helpers into codex-tools (#16499)

## Why

This is another straight-refactor step in the `codex-tools` migration.

`core/src/tools/handlers/tool_suggest.rs` still owned request/response
payload structs, elicitation metadata shaping, and connector-completion
predicates that do not depend on `codex-core` session/runtime internals.
Per the `AGENTS.md` guidance to keep shrinking `codex-core`, this moves
that pure wire-format logic into `codex-rs/tools` so the core handler
keeps only session orchestration, plugin/config refresh, and MCP cache
updates.

## What changed

- Added `codex-rs/tools/src/tool_suggest.rs` and exported its API from
`codex-rs/tools/src/lib.rs`.
- Moved `ToolSuggestArgs`, `ToolSuggestResult`, `ToolSuggestMeta`,
`build_tool_suggestion_elicitation_request()`,
`all_suggested_connectors_picked_up()`, and
`verified_connector_suggestion_completed()` into `codex-tools`.
- Rewired `core/src/tools/handlers/tool_suggest.rs` to consume those
exports directly.
- Ported the existing pure helper tests from
`core/src/tools/handlers/tool_suggest_tests.rs` to
`tools/src/tool_suggest_tests.rs` without adding new behavior coverage.

## Validation

```shell
cargo test -p codex-tools
cargo test -p codex-core tools::handlers::tool_suggest::tests
just argument-comment-lint
```

codex-rs/tools/src/tool_suggest_tests.rs

@@ -0,0 +1,207 @@
+use super::*;
+use crate::DiscoverablePluginInfo;
+use pretty_assertions::assert_eq;
+use serde_json::json;
+
+#[test]
+fn build_tool_suggestion_elicitation_request_uses_expected_shape() {
+    let args = ToolSuggestArgs {
+        tool_type: DiscoverableToolType::Connector,
+        action_type: DiscoverableToolAction::Install,
+        tool_id: "connector_2128aebfecb84f64a069897515042a44".to_string(),
+        suggest_reason: "Plan and reference events from your calendar".to_string(),
+    };
+    let connector = DiscoverableTool::Connector(Box::new(AppInfo {
+        id: "connector_2128aebfecb84f64a069897515042a44".to_string(),
+        name: "Google Calendar".to_string(),
+        description: Some("Plan events and schedules.".to_string()),
+        logo_url: None,
+        logo_url_dark: None,
+        distribution_channel: None,
+        branding: None,
+        app_metadata: None,
+        labels: None,
+        install_url: Some(
+            "https://chatgpt.com/apps/google-calendar/connector_2128aebfecb84f64a069897515042a44"
+                .to_string(),
+        ),
+        is_accessible: false,
+        is_enabled: true,
+        plugin_display_names: Vec::new(),
+    }));
+
+    let request = build_tool_suggestion_elicitation_request(
+        "codex-apps",
+        "thread-1".to_string(),
+        "turn-1".to_string(),
+        &args,
+        "Plan and reference events from your calendar",
+        &connector,
+    );
+
+    assert_eq!(
+        request,
+        McpServerElicitationRequestParams {
+            thread_id: "thread-1".to_string(),
+            turn_id: Some("turn-1".to_string()),
+            server_name: "codex-apps".to_string(),
+            request: McpServerElicitationRequest::Form {
+                meta: Some(json!(ToolSuggestMeta {
+                    codex_approval_kind: TOOL_SUGGEST_APPROVAL_KIND_VALUE,
+                    tool_type: DiscoverableToolType::Connector,
+                    suggest_type: DiscoverableToolAction::Install,
+                    suggest_reason: "Plan and reference events from your calendar",
+                    tool_id: "connector_2128aebfecb84f64a069897515042a44",
+                    tool_name: "Google Calendar",
+                    install_url: Some(
+                        "https://chatgpt.com/apps/google-calendar/connector_2128aebfecb84f64a069897515042a44"
+                    ),
+                })),
+                message: "Plan and reference events from your calendar".to_string(),
+                requested_schema: McpElicitationSchema {
+                    schema_uri: None,
+                    type_: McpElicitationObjectType::Object,
+                    properties: BTreeMap::new(),
+                    required: None,
+                },
+            },
+        },
+    );
+}
+
+#[test]
+fn build_tool_suggestion_elicitation_request_for_plugin_omits_install_url() {
+    let args = ToolSuggestArgs {
+        tool_type: DiscoverableToolType::Plugin,
+        action_type: DiscoverableToolAction::Install,
+        tool_id: "sample@openai-curated".to_string(),
+        suggest_reason: "Use the sample plugin's skills and MCP server".to_string(),
+    };
+    let plugin = DiscoverableTool::Plugin(Box::new(DiscoverablePluginInfo {
+        id: "sample@openai-curated".to_string(),
+        name: "Sample Plugin".to_string(),
+        description: Some("Includes skills, MCP servers, and apps.".to_string()),
+        has_skills: true,
+        mcp_server_names: vec!["sample-docs".to_string()],
+        app_connector_ids: vec!["connector_calendar".to_string()],
+    }));
+
+    let request = build_tool_suggestion_elicitation_request(
+        "codex-apps",
+        "thread-1".to_string(),
+        "turn-1".to_string(),
+        &args,
+        "Use the sample plugin's skills and MCP server",
+        &plugin,
+    );
+
+    assert_eq!(
+        request,
+        McpServerElicitationRequestParams {
+            thread_id: "thread-1".to_string(),
+            turn_id: Some("turn-1".to_string()),
+            server_name: "codex-apps".to_string(),
+            request: McpServerElicitationRequest::Form {
+                meta: Some(json!(ToolSuggestMeta {
+                    codex_approval_kind: TOOL_SUGGEST_APPROVAL_KIND_VALUE,
+                    tool_type: DiscoverableToolType::Plugin,
+                    suggest_type: DiscoverableToolAction::Install,
+                    suggest_reason: "Use the sample plugin's skills and MCP server",
+                    tool_id: "sample@openai-curated",
+                    tool_name: "Sample Plugin",
+                    install_url: None,
+                })),
+                message: "Use the sample plugin's skills and MCP server".to_string(),
+                requested_schema: McpElicitationSchema {
+                    schema_uri: None,
+                    type_: McpElicitationObjectType::Object,
+                    properties: BTreeMap::new(),
+                    required: None,
+                },
+            },
+        },
+    );
+}
+
+#[test]
+fn build_tool_suggestion_meta_uses_expected_shape() {
+    let meta = build_tool_suggestion_meta(
+        DiscoverableToolType::Connector,
+        DiscoverableToolAction::Install,
+        "Find and reference emails from your inbox",
+        "connector_68df038e0ba48191908c8434991bbac2",
+        "Gmail",
+        Some("https://chatgpt.com/apps/gmail/connector_68df038e0ba48191908c8434991bbac2"),
+    );
+
+    assert_eq!(
+        meta,
+        ToolSuggestMeta {
+            codex_approval_kind: TOOL_SUGGEST_APPROVAL_KIND_VALUE,
+            tool_type: DiscoverableToolType::Connector,
+            suggest_type: DiscoverableToolAction::Install,
+            suggest_reason: "Find and reference emails from your inbox",
+            tool_id: "connector_68df038e0ba48191908c8434991bbac2",
+            tool_name: "Gmail",
+            install_url: Some(
+                "https://chatgpt.com/apps/gmail/connector_68df038e0ba48191908c8434991bbac2"
+            ),
+        },
+    );
+}
+
+#[test]
+fn verified_connector_suggestion_completed_requires_accessible_connector() {
+    let accessible_connectors = vec![AppInfo {
+        id: "calendar".to_string(),
+        name: "Google Calendar".to_string(),
+        description: None,
+        logo_url: None,
+        logo_url_dark: None,
+        distribution_channel: None,
+        branding: None,
+        app_metadata: None,
+        labels: None,
+        install_url: None,
+        is_accessible: true,
+        is_enabled: false,
+        plugin_display_names: Vec::new(),
+    }];
+
+    assert!(verified_connector_suggestion_completed(
+        "calendar",
+        &accessible_connectors,
+    ));
+    assert!(!verified_connector_suggestion_completed(
+        "gmail",
+        &accessible_connectors,
+    ));
+}
+
+#[test]
+fn all_suggested_connectors_picked_up_requires_every_expected_connector() {
+    let accessible_connectors = vec![AppInfo {
+        id: "calendar".to_string(),
+        name: "Google Calendar".to_string(),
+        description: None,
+        logo_url: None,
+        logo_url_dark: None,
+        distribution_channel: None,
+        branding: None,
+        app_metadata: None,
+        labels: None,
+        install_url: None,
+        is_accessible: true,
+        is_enabled: false,
+        plugin_display_names: Vec::new(),
+    }];
+
+    assert!(all_suggested_connectors_picked_up(
+        &["calendar".to_string()],
+        &accessible_connectors,
+    ));
+    assert!(!all_suggested_connectors_picked_up(
+        &["calendar".to_string(), "gmail".to_string()],
+        &accessible_connectors,
+    ));
+}