[codex] Support object-valued plugin MCP manifests

[charlesgong-openai]

Summary

This fixes plugin manifest parsing for MCP servers declared as an object directly in plugin.json.

Before this change, Codex modeled mcpServers as only a string path, for example:

{
  "name": "counter-sample",
  "version": "1.1.1",
  "mcpServers": "./.mcp.json"
}

Some migrated plugins instead provide the server map directly in the manifest:

{
  "name": "counter-sample",
  "version": "1.1.1",
  "description": "Plugin that declares MCP servers in the manifest",
  "mcpServers": {
    "counter": {
      "type": "http",
      "url": "https://sample.example/counter/mcp"
    }
  }
}

That object form previously failed during install/load with an error like:

failed to parse plugin manifest: invalid type: map, expected a string

What changed

• Add a manifest representation for mcpServers as either Path(Resource) or Object(map).
• Parse plugin.json mcpServers as either a string path or an object.
• Route object-valued MCP server maps through the existing plugin MCP config parser instead of adding a second parser.
• Apply existing per-plugin MCP server policy to object-valued MCP servers the same way as file-backed MCP servers.
• Include object-valued MCP server names in plugin telemetry/capability metadata.
• Support object-valued MCP config for executor plugins without requiring a .mcp.json filesystem read.
• Update the bundled plugin-creator validator and plugin-json-spec.md so generated-plugin validation accepts the same object-valued shape.

Compatibility

Existing plugin manifests that use "mcpServers": "./.mcp.json" continue to work. Plugins can now also use the object shape shown above.

Tests

Added coverage for the new manifest attribute shape at the install, normal load, telemetry, and executor-provider layers:

• install_accepts_manifest_mcp_server_objects
• load_plugins_loads_manifest_mcp_server_objects
• plugin_telemetry_metadata_uses_manifest_mcp_server_objects
• reads_manifest_object_config_without_executor_file_system_access

Also smoke-tested the plugin-creator validator against both supported forms:

• mcpServers as a direct object in plugin.json
• mcpServers as "./.mcp.json" with a companion .mcp.json

Validation

• just test -p codex-plugin
• just test -p codex-core-plugins
• just test -p codex-mcp-extension
• just bazel-lock-update
• just bazel-lock-check
• just fmt
• git diff --check
• Focused rename/object-form rerun: just test -p codex-core-plugins manager::tests::load_plugins_loads_manifest_mcp_server_objects manager::tests::plugin_telemetry_metadata_uses_manifest_mcp_server_objects store::tests::install_accepts_manifest_mcp_server_objects
• Focused executor rerun: just test -p codex-mcp-extension executor_plugin::provider::tests::reads_manifest_object_config_without_executor_file_system_access
• python3 codex-rs/skills/src/assets/samples/plugin-creator/scripts/validate_plugin.py /private/tmp/codex-validator-object
• python3 codex-rs/skills/src/assets/samples/plugin-creator/scripts/validate_plugin.py /private/tmp/codex-validator-path

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 36acfc8d0d

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".