Story 46: Deterministic Story Mutations with Auto-Commit

- Add git_stage_and_commit() helper for deterministic commits
- move_story_to_current() auto-commits on start_agent
- accept_story auto-commits move to archived/
- New MCP tools: check_criterion, set_test_plan (total: 21)
- create_story MCP always auto-commits
- Tests for check_criterion and set_test_plan

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/http/mcp.rs

@@ -2,7 +2,10 @@ use crate::agents::move_story_to_archived;
 use crate::config::ProjectConfig;
 use crate::http::context::AppContext;
 use crate::http::settings::get_editor_command_from_store;
-use crate::http::workflow::{create_story_file, load_upcoming_stories, validate_story_dirs};
+use crate::http::workflow::{
+    check_criterion_in_file, create_story_file, load_upcoming_stories, set_test_plan_in_file,
+    validate_story_dirs,
+};
 use crate::worktree;
 use crate::io::story_metadata::{parse_front_matter, parse_unchecked_todos};
 use crate::workflow::{evaluate_acceptance_with_coverage, TestCaseResult, TestStatus};
@@ -603,7 +606,7 @@ fn handle_tools_list(id: Option<Value>) -> JsonRpcResponse {
                 },
                 {
                     "name": "accept_story",
-                    "description": "Accept a story: moves it from current/ to archived/.",
+                    "description": "Accept a story: moves it from current/ to archived/ and auto-commits to master.",
                     "inputSchema": {
                         "type": "object",
                         "properties": {
@@ -614,6 +617,42 @@ fn handle_tools_list(id: Option<Value>) -> JsonRpcResponse {
                         },
                         "required": ["story_id"]
                     }
+                },
+                {
+                    "name": "check_criterion",
+                    "description": "Check off an acceptance criterion (- [ ] → - [x]) by 0-based index among unchecked items, then auto-commit to master. Use get_story_todos to see the current list of unchecked criteria.",
+                    "inputSchema": {
+                        "type": "object",
+                        "properties": {
+                            "story_id": {
+                                "type": "string",
+                                "description": "Story identifier (filename stem, e.g. '28_my_story')"
+                            },
+                            "criterion_index": {
+                                "type": "integer",
+                                "description": "0-based index of the unchecked criterion to check off"
+                            }
+                        },
+                        "required": ["story_id", "criterion_index"]
+                    }
+                },
+                {
+                    "name": "set_test_plan",
+                    "description": "Update the test_plan front-matter field of a story file and auto-commit to master. Common values: 'pending', 'approved'.",
+                    "inputSchema": {
+                        "type": "object",
+                        "properties": {
+                            "story_id": {
+                                "type": "string",
+                                "description": "Story identifier (filename stem, e.g. '28_my_story')"
+                            },
+                            "status": {
+                                "type": "string",
+                                "description": "New value for the test_plan field (e.g. 'approved', 'pending')"
+                            }
+                        },
+                        "required": ["story_id", "status"]
+                    }
                 }
             ]
         }),
@@ -659,6 +698,9 @@ async fn handle_tools_call(
         "report_completion" => tool_report_completion(&args, ctx).await,
         // Lifecycle tools
         "accept_story" => tool_accept_story(&args, ctx),
+        // Story mutation tools (auto-commit to master)
+        "check_criterion" => tool_check_criterion(&args, ctx),
+        "set_test_plan" => tool_set_test_plan(&args, ctx),
         _ => Err(format!("Unknown tool: {tool_name}")),
     };
 
@@ -690,10 +732,8 @@ fn tool_create_story(args: &Value, ctx: &AppContext) -> Result<String, String> {
     let acceptance_criteria: Option<Vec<String>> = args
         .get("acceptance_criteria")
         .and_then(|v| serde_json::from_value(v.clone()).ok());
-    let commit = args
-        .get("commit")
-        .and_then(|v| v.as_bool())
-        .unwrap_or(false);
+    // MCP tool always auto-commits the new story file to master.
+    let commit = true;
 
     let root = ctx.state.get_project_root()?;
     let story_id = create_story_file(
@@ -1067,7 +1107,45 @@ fn tool_accept_story(args: &Value, ctx: &AppContext) -> Result<String, String> {
     let project_root = ctx.agents.get_project_root(&ctx.state)?;
     move_story_to_archived(&project_root, story_id)?;
 
-    Ok(format!("Story '{story_id}' accepted and moved to archived/."))
+    Ok(format!(
+        "Story '{story_id}' accepted, moved to archived/, and committed to master."
+    ))
+}
+
+fn tool_check_criterion(args: &Value, ctx: &AppContext) -> Result<String, String> {
+    let story_id = args
+        .get("story_id")
+        .and_then(|v| v.as_str())
+        .ok_or("Missing required argument: story_id")?;
+    let criterion_index = args
+        .get("criterion_index")
+        .and_then(|v| v.as_u64())
+        .ok_or("Missing required argument: criterion_index")? as usize;
+
+    let root = ctx.state.get_project_root()?;
+    check_criterion_in_file(&root, story_id, criterion_index)?;
+
+    Ok(format!(
+        "Criterion {criterion_index} checked for story '{story_id}'. Committed to master."
+    ))
+}
+
+fn tool_set_test_plan(args: &Value, ctx: &AppContext) -> Result<String, String> {
+    let story_id = args
+        .get("story_id")
+        .and_then(|v| v.as_str())
+        .ok_or("Missing required argument: story_id")?;
+    let status = args
+        .get("status")
+        .and_then(|v| v.as_str())
+        .ok_or("Missing required argument: status")?;
+
+    let root = ctx.state.get_project_root()?;
+    set_test_plan_in_file(&root, story_id, status)?;
+
+    Ok(format!(
+        "test_plan set to '{status}' for story '{story_id}'. Committed to master."
+    ))
 }
 
 /// Run `git log <base>..HEAD --oneline` in the worktree and return the commit
@@ -1222,7 +1300,9 @@ mod tests {
         assert!(names.contains(&"get_editor_command"));
         assert!(names.contains(&"report_completion"));
         assert!(names.contains(&"accept_story"));
-        assert_eq!(tools.len(), 19);
+        assert!(names.contains(&"check_criterion"));
+        assert!(names.contains(&"set_test_plan"));
+        assert_eq!(tools.len(), 21);
     }
 
     #[test]
@@ -1253,11 +1333,32 @@ mod tests {
     #[test]
     fn tool_create_story_and_list_upcoming() {
         let tmp = tempfile::tempdir().unwrap();
+        // The MCP tool always commits, so we need a real git repo.
+        std::process::Command::new("git")
+            .args(["init"])
+            .current_dir(tmp.path())
+            .output()
+            .unwrap();
+        std::process::Command::new("git")
+            .args(["config", "user.email", "test@test.com"])
+            .current_dir(tmp.path())
+            .output()
+            .unwrap();
+        std::process::Command::new("git")
+            .args(["config", "user.name", "Test"])
+            .current_dir(tmp.path())
+            .output()
+            .unwrap();
+        std::process::Command::new("git")
+            .args(["commit", "--allow-empty", "-m", "init"])
+            .current_dir(tmp.path())
+            .output()
+            .unwrap();
         let ctx = test_ctx(tmp.path());
 
-        // Create a story
+        // Create a story (always auto-commits in MCP handler)
         let result = tool_create_story(
-            &json!({"name": "Test Story", "acceptance_criteria": ["AC1", "AC2"], "commit": false}),
+            &json!({"name": "Test Story", "acceptance_criteria": ["AC1", "AC2"]}),
             &ctx,
         )
         .unwrap();