mirror of
https://github.com/openai/codex.git
synced 2026-09-05 15:18:41 +00:00
## Why
An MCP refresh can replace the session's current manager while a model
step is still running. The step must execute calls through the same
manager whose tools it advertised.
## Boundary
```text
current session MCP runtime
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| capture once for this model step
v
StepContext.mcp
- exact MCP config
- exact connection manager
- exact runtime environment context
```
```rust
pub struct McpRuntimeSnapshot {
config: Arc<McpConfig>,
manager: Arc<McpConnectionManager>,
runtime_context: McpRuntimeContext,
}
```
## Example
```text
step A captures runtime A and advertises A's tools
refresh publishes runtime B
step A tool call -> runtime A
next step -> runtime B
```
Capturing the snapshot is only an `Arc` clone. It does not restart MCPs
or make an RPC.
## What changes
- Captures one MCP runtime in `StepContext`.
- Uses it for tool planning, tool calls, resources, approvals, connector
attribution, and elicitation.
- Publishes replacement runtimes atomically.
- Lets an old runtime live only while an in-flight step or request still
holds its `Arc`.
Most of this diff is mechanical routing from the session-global manager
to `step_context.mcp`; it does not introduce selected-plugin discovery
yet.
## What does not change
- No plugin or extension migration.
- No new MCP cache policy.
- No environment file watching.
- No client sharing between separate managers.
## Stack
1. Extension-owned World State sections.
2. Project executor skills through World State.
3. **This PR:** pin one MCP runtime to each model step.
4. Project selected MCP/app/connector metadata by environment
availability.
5. One end-to-end integration scenario.
408 lines
12 KiB
Rust
408 lines
12 KiB
Rust
use std::collections::HashMap;
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use std::time::Duration;
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use codex_config::AppToolApproval;
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use codex_config::DEFAULT_MCP_SERVER_ENVIRONMENT_ID;
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use codex_config::McpServerConfig;
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use codex_config::McpServerToolConfig;
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use codex_config::McpServerTransportConfig;
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use pretty_assertions::assert_eq;
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use super::McpPluginAttribution;
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use super::McpServerConflict;
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use super::McpServerConflictAction;
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use super::McpServerRegistration;
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use super::McpServerSource;
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use super::ResolvedMcpCatalog;
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fn server(url: &str) -> McpServerConfig {
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McpServerConfig {
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auth: Default::default(),
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transport: McpServerTransportConfig::StreamableHttp {
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url: url.to_string(),
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bearer_token_env_var: None,
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http_headers: None,
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env_http_headers: None,
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},
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environment_id: DEFAULT_MCP_SERVER_ENVIRONMENT_ID.to_string(),
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enabled: true,
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required: true,
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supports_parallel_tool_calls: true,
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disabled_reason: None,
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startup_timeout_sec: Some(Duration::from_secs(7)),
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tool_timeout_sec: Some(Duration::from_secs(11)),
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default_tools_approval_mode: Some(AppToolApproval::Prompt),
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enabled_tools: Some(vec!["read".to_string()]),
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disabled_tools: Some(vec!["write".to_string()]),
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scopes: None,
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oauth: None,
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oauth_resource: None,
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tools: HashMap::from([(
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"read".to_string(),
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McpServerToolConfig {
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approval_mode: Some(AppToolApproval::Approve),
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},
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)]),
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}
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}
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fn plugin(plugin_id: &str) -> McpPluginAttribution {
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McpPluginAttribution::new(plugin_id.to_string(), plugin_id.to_string())
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}
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fn plugin_source(plugin_id: &str) -> McpServerSource {
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McpServerSource::Plugin(plugin(plugin_id))
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}
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fn selected_plugin_source(plugin_id: &str) -> McpServerSource {
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McpServerSource::SelectedPlugin(plugin(plugin_id))
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}
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fn compatibility_source(id: &str) -> McpServerSource {
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McpServerSource::Compatibility { id: id.to_string() }
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}
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fn extension_source(id: &str) -> McpServerSource {
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McpServerSource::Extension { id: id.to_string() }
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}
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fn register(source: McpServerSource) -> McpServerConflictAction {
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McpServerConflictAction::Register(source)
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}
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fn remove(source: McpServerSource) -> McpServerConflictAction {
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McpServerConflictAction::Remove(source)
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}
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#[test]
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fn source_precedence_preserves_the_winning_registration() {
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let extension = server("https://extension.example/mcp");
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let mut plugin_server = server("https://plugin.example/mcp");
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plugin_server.enabled = false;
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_extension(
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"docs".to_string(),
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"hosted",
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/*contribution_order*/ 0,
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extension.clone(),
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));
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builder.register(McpServerRegistration::from_plugin(
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"docs".to_string(),
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plugin("plugin@test"),
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/*plugin_order*/ 0,
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plugin_server,
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));
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builder.register(McpServerRegistration::from_plugin(
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"docs".to_string(),
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plugin("other-plugin@test"),
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/*plugin_order*/ 1,
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server("https://other-plugin.example/mcp"),
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));
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builder.register(McpServerRegistration::from_compatibility(
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"docs".to_string(),
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"legacy",
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server("https://compatibility.example/mcp"),
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));
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builder.register(McpServerRegistration::from_config(
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"docs".to_string(),
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server("https://config.example/mcp"),
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));
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let catalog = builder.build();
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let resolved = catalog.server("docs").expect("resolved server");
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assert_eq!(
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resolved.source(),
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&McpServerSource::Extension {
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id: "hosted".to_string(),
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}
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);
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assert_eq!(resolved.config(), &extension);
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assert!(catalog.plugin_attributions_by_server_name().is_empty());
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assert_eq!(
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catalog.conflicts(),
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&[McpServerConflict {
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name: "docs".to_string(),
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outcome: register(extension_source("hosted")),
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contenders: vec![
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register(plugin_source("other-plugin@test")),
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register(plugin_source("plugin@test")),
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],
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}]
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);
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}
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#[test]
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fn disabled_veto_only_disables_the_winning_registration() {
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let extension = server("https://extension.example/mcp");
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let mut expected = extension.clone();
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expected.enabled = false;
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_extension(
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"docs".to_string(),
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"hosted",
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/*contribution_order*/ 0,
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extension,
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));
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builder.disable("docs".to_string());
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let actual = builder
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.build()
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.server("docs")
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.expect("resolved server")
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.config()
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.clone();
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assert_eq!(actual, expected);
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}
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#[test]
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fn disabled_winner_remains_a_veto_when_the_catalog_is_extended() {
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let mut disabled = server("https://config.example/mcp");
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disabled.enabled = false;
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let mut expected = server("https://extension.example/mcp");
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expected.enabled = false;
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_config(
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"docs".to_string(),
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disabled,
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));
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let mut builder = builder.build().to_builder();
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builder.register(McpServerRegistration::from_extension(
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"docs".to_string(),
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"hosted",
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/*contribution_order*/ 0,
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server("https://extension.example/mcp"),
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));
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let resolved = builder.build();
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assert_eq!(
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resolved.server("docs"),
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Some(&super::ResolvedMcpServer {
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source: extension_source("hosted"),
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config: expected,
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})
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);
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}
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#[test]
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fn disabled_discovered_plugin_remains_a_veto_for_runtime_overlays() {
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let mut disabled = server("https://plugin.example/mcp");
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disabled.enabled = false;
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let mut expected = server("https://extension.example/mcp");
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expected.enabled = false;
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_plugin(
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"docs".to_string(),
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plugin("plugin@test"),
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/*plugin_order*/ 0,
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disabled,
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));
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let mut builder = builder.build().to_builder();
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builder.register(McpServerRegistration::from_extension(
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"docs".to_string(),
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"hosted",
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/*contribution_order*/ 0,
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server("https://extension.example/mcp"),
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));
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let resolved = builder.build();
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assert_eq!(
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resolved.server("docs"),
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Some(&super::ResolvedMcpServer {
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source: extension_source("hosted"),
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config: expected,
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})
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);
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}
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#[test]
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fn earlier_plugin_wins_with_an_explicit_conflict() {
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_plugin(
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"docs".to_string(),
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plugin("alpha@test"),
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/*plugin_order*/ 0,
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server("https://alpha.example/mcp"),
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));
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builder.register(McpServerRegistration::from_plugin(
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"docs".to_string(),
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plugin("beta@test"),
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/*plugin_order*/ 1,
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server("https://beta.example/mcp"),
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));
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let catalog = builder.build();
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assert_eq!(
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catalog.plugin_attributions_by_server_name(),
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HashMap::from([("docs".to_string(), plugin("alpha@test"))])
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);
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assert_eq!(
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catalog.conflicts(),
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&[McpServerConflict {
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name: "docs".to_string(),
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outcome: register(plugin_source("alpha@test")),
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contenders: vec![
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register(plugin_source("beta@test")),
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register(plugin_source("alpha@test")),
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],
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}]
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);
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}
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#[test]
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fn selected_plugins_override_discovered_plugins_but_not_config() {
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let selected = server("https://selected-alpha.example/mcp");
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let mut discovered = server("https://local.example/mcp");
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discovered.enabled = false;
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discovered.default_tools_approval_mode = Some(AppToolApproval::Auto);
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_plugin(
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"docs".to_string(),
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plugin("local@test"),
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/*plugin_order*/ 0,
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discovered,
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));
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builder.register(McpServerRegistration::from_selected_plugin(
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"docs".to_string(),
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plugin("selected-beta"),
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/*selection_order*/ 1,
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server("https://selected-beta.example/mcp"),
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));
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builder.register(McpServerRegistration::from_selected_plugin(
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"docs".to_string(),
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plugin("selected-alpha"),
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/*selection_order*/ 0,
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selected.clone(),
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));
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let catalog = builder.build();
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assert_eq!(
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catalog.server("docs"),
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Some(&super::ResolvedMcpServer {
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source: selected_plugin_source("selected-alpha"),
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config: selected,
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})
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);
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assert_eq!(
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catalog.plugin_attributions_by_server_name(),
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HashMap::from([("docs".to_string(), plugin("selected-alpha"))])
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);
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assert_eq!(
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catalog.conflicts(),
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&[McpServerConflict {
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name: "docs".to_string(),
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outcome: register(selected_plugin_source("selected-alpha")),
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contenders: vec![
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register(selected_plugin_source("selected-beta")),
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register(selected_plugin_source("selected-alpha")),
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],
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}]
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);
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let refreshed = server("https://refreshed.example/mcp");
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let catalog =
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catalog.with_materialized_servers(HashMap::from([("docs".to_string(), refreshed.clone())]));
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assert_eq!(
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catalog.server("docs"),
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Some(&super::ResolvedMcpServer {
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source: selected_plugin_source("selected-alpha"),
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config: refreshed,
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})
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);
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let mut builder = catalog.to_builder();
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let configured = server("https://config.example/mcp");
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builder.register(McpServerRegistration::from_config(
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"docs".to_string(),
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configured.clone(),
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));
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let catalog = builder.build();
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assert_eq!(
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catalog.server("docs"),
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Some(&super::ResolvedMcpServer {
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source: McpServerSource::Config,
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config: configured,
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})
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);
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}
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#[test]
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fn disabled_selected_plugin_does_not_veto_runtime_overlays() {
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let mut disabled = server("https://selected.example/mcp");
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disabled.enabled = false;
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let extension = server("https://extension.example/mcp");
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_selected_plugin(
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"docs".to_string(),
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plugin("selected"),
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/*selection_order*/ 0,
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disabled,
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));
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let mut builder = builder.build().to_builder();
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builder.register(McpServerRegistration::from_extension(
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"docs".to_string(),
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"hosted",
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/*contribution_order*/ 0,
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extension.clone(),
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));
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let resolved = builder.build();
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assert_eq!(
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resolved.server("docs"),
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Some(&super::ResolvedMcpServer {
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source: extension_source("hosted"),
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config: extension,
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})
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);
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}
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#[test]
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fn equal_precedence_uses_insertion_order_not_source_identity() {
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let mut builder = ResolvedMcpCatalog::builder();
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builder.register(McpServerRegistration::from_compatibility(
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"docs".to_string(),
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"z-first",
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server("https://first.example/mcp"),
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));
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builder.register(McpServerRegistration::from_compatibility(
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"docs".to_string(),
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"a-second",
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server("https://second.example/mcp"),
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));
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let catalog = builder.build();
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assert_eq!(
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catalog.server("docs"),
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Some(&super::ResolvedMcpServer {
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source: compatibility_source("a-second"),
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config: server("https://second.example/mcp"),
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})
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);
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let mut builder = catalog.to_builder();
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builder.remove_compatibility("docs".to_string(), "remove-last");
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let catalog = builder.build();
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assert_eq!(catalog.server("docs"), None);
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assert_eq!(
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catalog.conflicts(),
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&[McpServerConflict {
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name: "docs".to_string(),
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outcome: remove(compatibility_source("remove-last")),
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contenders: vec![
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register(compatibility_source("z-first")),
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register(compatibility_source("a-second")),
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remove(compatibility_source("remove-last")),
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],
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}]
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);
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}
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