huskies: merge 652_story_pass_resume_session_id_on_agent_respawn_so_new_sessions_inherit_prior_reasoning

server/src/agents/pool/start/mod.rs

@@ -292,6 +292,22 @@ impl AgentPool {
             .map(|a| a.inactivity_timeout_secs)
             .unwrap_or(300);
 
+        // If no explicit session_id_to_resume was provided, look up from the
+        // persistent session store.  The key includes the model so a model
+        // change (e.g. sonnet → opus) produces a cache miss — intentional.
+        let effective_session_id = session_id_to_resume.or_else(|| {
+            let model = config
+                .find_agent(&resolved_name)
+                .and_then(|a| a.model.clone())
+                .unwrap_or_default();
+            crate::agents::session_store::lookup_session(
+                project_root,
+                story_id,
+                &resolved_name,
+                &model,
+            )
+        });
+
         // Clone all values needed inside the background spawn.
         // Spawn the background task. Worktree creation and agent launch happen here
         // so `start_agent` returns immediately after registering the agent as
@@ -300,7 +316,7 @@ impl AgentPool {
             project_root.to_path_buf(),
             config.clone(),
             resume_context.map(str::to_string),
-            session_id_to_resume,
+            effective_session_id,
             story_id.to_string(),
             resolved_name.clone(),
             tx.clone(),

server/src/agents/pool/start/spawn.rs

@@ -155,13 +155,17 @@ pub(super) async fn run_agent_spawn(
     // (which would re-read CLAUDE.md and README) and send only the gate
     // failure context as a new message.  On a fresh start, append the
     // failure context to the original prompt as before.
-    let effective_prompt = match &session_id_to_resume_owned {
-        Some(_) => resume_context_owned.unwrap_or_default(),
+    let (effective_prompt, fresh_prompt) = match &session_id_to_resume_owned {
+        Some(_) => {
+            // Keep the full rendered prompt as fallback if resume fails.
+            let fallback = prompt;
+            (resume_context_owned.unwrap_or_default(), Some(fallback))
+        }
         None => {
             if let Some(ctx) = resume_context_owned {
                 prompt.push_str(&ctx);
             }
-            prompt
+            (prompt, None)
         }
     };
 
@@ -200,6 +204,7 @@ pub(super) async fn run_agent_spawn(
                 inactivity_timeout_secs,
                 mcp_port: port_for_task,
                 session_id_to_resume: session_id_to_resume_owned.clone(),
+                fresh_prompt: fresh_prompt.clone(),
             };
             runtime
                 .start(ctx, tx_clone.clone(), log_clone.clone(), log_writer_clone)
@@ -217,6 +222,7 @@ pub(super) async fn run_agent_spawn(
                 inactivity_timeout_secs,
                 mcp_port: port_for_task,
                 session_id_to_resume: session_id_to_resume_owned.clone(),
+                fresh_prompt: fresh_prompt.clone(),
             };
             runtime
                 .start(ctx, tx_clone.clone(), log_clone.clone(), log_writer_clone)
@@ -234,6 +240,7 @@ pub(super) async fn run_agent_spawn(
                 inactivity_timeout_secs,
                 mcp_port: port_for_task,
                 session_id_to_resume: session_id_to_resume_owned,
+                fresh_prompt,
             };
             runtime
                 .start(ctx, tx_clone.clone(), log_clone.clone(), log_writer_clone)
@@ -266,6 +273,21 @@ pub(super) async fn run_agent_spawn(
                 }
             }
 
+            // Persist session_id so respawns can resume prior reasoning.
+            if let Some(ref sess_id) = result.session_id {
+                let model = config_clone
+                    .find_agent(&aname)
+                    .and_then(|a| a.model.clone())
+                    .unwrap_or_default();
+                crate::agents::session_store::record_session(
+                    &project_root_clone,
+                    &sid,
+                    &aname,
+                    &model,
+                    sess_id,
+                );
+            }
+
             // Mergemaster agents have their own completion path via
             // start_merge_agent_work / run_merge_pipeline and must NOT go
             // through server-owned gates.  When a mergemaster exits early