Split DeveloperInstructions into individual fragments. (#18813)

Split DeveloperInstructions into individual fragments.

codex-rs/core/src/plugins/injection.rs

@@ -2,10 +2,11 @@ use std::collections::BTreeSet;
 use std::collections::HashMap;
 
 use codex_connectors::metadata::connector_display_label;
-use codex_protocol::models::DeveloperInstructions;
 use codex_protocol::models::ResponseItem;
 
 use crate::connectors;
+use crate::context::ContextualUserFragment;
+use crate::context::PluginInstructions;
 use crate::plugins::PluginCapabilitySummary;
 use crate::plugins::render_explicit_plugin_instructions;
 use codex_mcp::CODEX_APPS_MCP_SERVER_NAME;
@@ -52,8 +53,8 @@ pub(crate) fn build_plugin_injections(
                 .into_iter()
                 .collect::<Vec<_>>();
             render_explicit_plugin_instructions(plugin, &available_mcp_servers, &available_apps)
-                .map(DeveloperInstructions::new)
-                .map(ResponseItem::from)
+                .map(PluginInstructions::new)
+                .map(ContextualUserFragment::into)
         })
         .collect()
 }

codex-rs/core/src/plugins/mod.rs

@@ -55,7 +55,6 @@ pub use marketplace_remove::MarketplaceRemoveOutcome;
 pub use marketplace_remove::MarketplaceRemoveRequest;
 pub use marketplace_remove::remove_marketplace;
 pub(crate) use render::render_explicit_plugin_instructions;
-pub(crate) use render::render_plugins_section;
 pub(crate) use startup_sync::curated_plugins_repo_path;
 pub(crate) use startup_sync::read_curated_plugins_sha;
 pub(crate) use startup_sync::sync_openai_plugins_repo;

codex-rs/core/src/plugins/render.rs

@@ -1,42 +1,12 @@
+#[cfg(test)]
+use crate::context::AvailablePluginsInstructions;
+#[cfg(test)]
+use crate::context::ContextualUserFragment;
 use crate::plugins::PluginCapabilitySummary;
-use codex_protocol::protocol::PLUGINS_INSTRUCTIONS_CLOSE_TAG;
-use codex_protocol::protocol::PLUGINS_INSTRUCTIONS_OPEN_TAG;
 
+#[cfg(test)]
 pub(crate) fn render_plugins_section(plugins: &[PluginCapabilitySummary]) -> Option<String> {
-    if plugins.is_empty() {
-        return None;
-    }
-
-    let mut lines = vec![
-        "## Plugins".to_string(),
-        "A plugin is a local bundle of skills, MCP servers, and apps. Below is the list of plugins that are enabled and available in this session.".to_string(),
-        "### Available plugins".to_string(),
-    ];
-
-    lines.extend(
-        plugins
-            .iter()
-            .map(|plugin| match plugin.description.as_deref() {
-                Some(description) => format!("- `{}`: {description}", plugin.display_name),
-                None => format!("- `{}`", plugin.display_name),
-            }),
-    );
-
-    lines.push("### How to use plugins".to_string());
-    lines.push(
-        r###"- Discovery: The list above is the plugins available in this session.
-- Skill naming: If a plugin contributes skills, those skill entries are prefixed with `plugin_name:` in the Skills list.
-- Trigger rules: If the user explicitly names a plugin, prefer capabilities associated with that plugin for that turn.
-- Relationship to capabilities: Plugins are not invoked directly. Use their underlying skills, MCP tools, and app tools to help solve the task.
-- Preference: When a relevant plugin is available, prefer using capabilities associated with that plugin over standalone capabilities that provide similar functionality.
-- Missing/blocked: If the user requests a plugin that is not listed above, or the plugin does not have relevant callable capabilities for the task, say so briefly and continue with the best fallback."###
-            .to_string(),
-    );
-
-    let body = lines.join("\n");
-    Some(format!(
-        "{PLUGINS_INSTRUCTIONS_OPEN_TAG}\n{body}\n{PLUGINS_INSTRUCTIONS_CLOSE_TAG}"
-    ))
+    AvailablePluginsInstructions::from_plugins(plugins).map(|instructions| instructions.render())
 }
 
 pub(crate) fn render_explicit_plugin_instructions(