Expose instruction sources (AGENTS.md) via app server (#17506)

Addresses #17498

Problem: The TUI derived /status instruction source paths from the local
client environment, which could show stale <none> output or incorrect
paths when connected to a remote app server.

Solution: Add an app-server v2 instructionSources snapshot to thread
start/resume/fork responses, default it to an empty list when older
servers omit it, and render TUI /status from that server-provided
session data.

Additional context: The app-server field is intentionally named
instructionSources rather than AGENTS.md-specific terminology because
the loaded instruction sources can include global instructions, project
AGENTS.md files, AGENTS.override.md, user-defined instruction files, and
future dynamic sources.

codex-rs/app-server/src/codex_message_processor.rs

@@ -239,6 +239,7 @@ use codex_core::sandboxing::SandboxPermissions;
 use codex_core::windows_sandbox::WindowsSandboxLevelExt;
 use codex_core::windows_sandbox::WindowsSandboxSetupMode as CoreWindowsSandboxSetupMode;
 use codex_core::windows_sandbox::WindowsSandboxSetupRequest;
+use codex_exec_server::LOCAL_FS;
 use codex_features::FEATURES;
 use codex_features::Feature;
 use codex_features::Stage;
@@ -491,6 +492,23 @@ pub(crate) struct CodexMessageProcessorArgs {
 }
 
 impl CodexMessageProcessor {
+    async fn instruction_sources_from_config(config: &Config) -> Vec<PathBuf> {
+        let mut paths: Vec<PathBuf> = config.user_instructions_path.iter().cloned().collect();
+        match codex_core::discover_project_doc_paths(config, LOCAL_FS.as_ref()).await {
+            Ok(project_doc_paths) => {
+                paths.extend(
+                    project_doc_paths
+                        .into_iter()
+                        .map(|path| path.as_path().to_path_buf()),
+                );
+            }
+            Err(err) => {
+                tracing::warn!(error = %err, "failed to discover project docs for thread response");
+            }
+        }
+        paths
+    }
+
     pub(crate) fn handle_config_mutation(&self) {
         self.clear_plugin_related_caches();
     }
@@ -2312,6 +2330,7 @@ impl CodexMessageProcessor {
             };
         }
 
+        let instruction_sources = Self::instruction_sources_from_config(&config).await;
         let dynamic_tools = dynamic_tools.unwrap_or_default();
         let core_dynamic_tools = if dynamic_tools.is_empty() {
             Vec::new()
@@ -2443,6 +2462,7 @@ impl CodexMessageProcessor {
                     model_provider: config_snapshot.model_provider_id,
                     service_tier: config_snapshot.service_tier,
                     cwd: config_snapshot.cwd,
+                    instruction_sources,
                     approval_policy: config_snapshot.approval_policy.into(),
                     approvals_reviewer: config_snapshot.approvals_reviewer.into(),
                     sandbox: config_snapshot.sandbox_policy.into(),
@@ -3881,6 +3901,7 @@ impl CodexMessageProcessor {
         };
 
         let fallback_model_provider = config.model_provider_id.clone();
+        let instruction_sources = Self::instruction_sources_from_config(&config).await;
         let response_history = thread_history.clone();
 
         match self
@@ -3961,6 +3982,7 @@ impl CodexMessageProcessor {
                     model_provider: session_configured.model_provider_id,
                     service_tier: session_configured.service_tier,
                     cwd: session_configured.cwd,
+                    instruction_sources,
                     approval_policy: session_configured.approval_policy.into(),
                     approvals_reviewer: session_configured.approvals_reviewer.into(),
                     sandbox: session_configured.sandbox_policy.into(),
@@ -4119,6 +4141,12 @@ impl CodexMessageProcessor {
                     mismatch_details.join("; ")
                 );
             }
+            let mut config_for_instruction_sources = self.config.as_ref().clone();
+            if let Ok(cwd) = AbsolutePathBuf::try_from(config_snapshot.cwd.clone()) {
+                config_for_instruction_sources.cwd = cwd;
+            }
+            let instruction_sources =
+                Self::instruction_sources_from_config(&config_for_instruction_sources).await;
             let thread_summary = match load_thread_summary_for_rollout(
                 &self.config,
                 existing_thread_id,
@@ -4156,6 +4184,7 @@ impl CodexMessageProcessor {
                     request_id: request_id.clone(),
                     rollout_path: rollout_path.clone(),
                     config_snapshot,
+                    instruction_sources,
                     thread_summary,
                 }),
             );
@@ -4431,6 +4460,7 @@ impl CodexMessageProcessor {
         };
 
         let fallback_model_provider = config.model_provider_id.clone();
+        let instruction_sources = Self::instruction_sources_from_config(&config).await;
 
         let NewThread {
             thread_id,
@@ -4585,6 +4615,7 @@ impl CodexMessageProcessor {
             model_provider: session_configured.model_provider_id,
             service_tier: session_configured.service_tier,
             cwd: session_configured.cwd,
+            instruction_sources,
             approval_policy: session_configured.approval_policy.into(),
             approvals_reviewer: session_configured.approvals_reviewer.into(),
             sandbox: session_configured.sandbox_policy.into(),
@@ -8156,12 +8187,14 @@ async fn handle_pending_thread_resume_request(
         reasoning_effort,
         ..
     } = pending.config_snapshot;
+    let instruction_sources = pending.instruction_sources;
     let response = ThreadResumeResponse {
         thread,
         model,
         model_provider: model_provider_id,
         service_tier,
         cwd,
+        instruction_sources,
         approval_policy: approval_policy.into(),
         approvals_reviewer: approvals_reviewer.into(),
         sandbox: sandbox_policy.into(),