fix: harden merge-back recovery states

Treat in-progress non-conflicted merges as recoverable during merge-back preparation and make the recovery path less brittle after manual intervention. This preserves the existing merge-back flow while letting resumed cleanup-phase runs progress instead of failing on already-prepared git states.

Author: foglerek

packages/core/src/cli/post-run-merge-back-support.ts

@@ -142,6 +142,17 @@ export async function prepareMergeBackMerge(args: {
     };
   }
 
+  if (!mergeInProgress && statusBefore.stdout.trim().length > 0) {
+    return {
+      alreadyPrepared: false,
+      earlyResult: {
+        status: "aborted",
+        message:
+          "Merge-back aborted: main repo has uncommitted changes. Commit/stash first and rerun resume.",
+      },
+    };
+  }
+
   const branchCheck = await ensureBaseBranchCheckedOut({
     exec: args.exec,
     prompt: args.prompt,
@@ -180,17 +191,6 @@ export async function prepareMergeBackMerge(args: {
     return { alreadyPrepared: true, earlyResult: null };
   }
 
-  if (statusBefore.stdout.trim().length > 0) {
-    return {
-      alreadyPrepared: false,
-      earlyResult: {
-        status: "aborted",
-        message:
-          "Merge-back aborted: main repo has uncommitted changes. Commit/stash first and rerun resume.",
-      },
-    };
-  }
-
   const alreadyMerged = await runGit(args.exec, args.repoPath, [
     "merge-base",
     "--is-ancestor",

packages/core/src/cli/post-run-merge-back.ts

@@ -78,6 +78,10 @@ function summarizeFirstFailure(
   return detail ? `${failed.name}: ${detail}` : failed.name;
 }
 
+function isNoOpCommitMessage(message: string): boolean {
+  return /nothing to commit, working tree clean/i.test(message);
+}
+
 function makeExecWithDefaults(state: OttoStateV1): OttoExec {
   const rawExec = createNodeExec();
   const defaultEnv = buildRunDefaultEnv(state);
@@ -353,8 +357,17 @@ export async function maybeRunPostCleanupMergeBack(args: {
     `Merge ${worktreeBranch} after Otto run ${state.runId}`,
   ], 60_000);
   if (commit.exitCode !== 0 || commit.timedOut) {
-    await abortPendingMerge(exec, repoPath);
     const commitMessage = (commit.stderr || commit.stdout || "git commit failed").trim();
+    if (isNoOpCommitMessage(commitMessage)) {
+      const mergeHead = await runGit(exec, repoPath, ["rev-parse", "--verify", "--quiet", "MERGE_HEAD"], 30_000);
+      if (mergeHead.exitCode !== 0 || mergeHead.timedOut) {
+        return {
+          status: "skipped",
+          message: `Skipped merge-back: ${worktreeBranch} is already merged into ${baseBranch}.`,
+        };
+      }
+    }
+    await abortPendingMerge(exec, repoPath);
     return {
       status: "failed",
       message: `Merge-back failed while committing merge: ${commitMessage}`,

packages/core/test/post-run-merge-back.test.js

@@ -114,6 +114,7 @@ test("merge-back aborts when main repo has uncommitted changes", async () => {
       match:
         "git rev-parse --verify --quiet workflow-2026-03-22-expo-graphql-resolvers",
     },
+    { match: "git rev-parse --verify --quiet MERGE_HEAD", result: { exitCode: 1 } },
     { match: "git status --porcelain=v1", result: { stdout: " M package.json\n" } },
   ]);
 
@@ -136,6 +137,7 @@ test("merge-back runs checks and commits on success", async () => {
       match:
         "git rev-parse --verify --quiet workflow-2026-03-22-expo-graphql-resolvers",
     },
+    { match: "git rev-parse --verify --quiet MERGE_HEAD", result: { exitCode: 1 } },
     { match: "git status --porcelain=v1" },
     { match: "git rev-parse --abbrev-ref HEAD", result: { stdout: "main\n" } },
     {
@@ -194,6 +196,7 @@ test("merge-back aborts merge when post-merge checks fail", async () => {
       match:
         "git rev-parse --verify --quiet workflow-2026-03-22-expo-graphql-resolvers",
     },
+    { match: "git rev-parse --verify --quiet MERGE_HEAD", result: { exitCode: 1 } },
     { match: "git status --porcelain=v1" },
     { match: "git rev-parse --abbrev-ref HEAD", result: { stdout: "main\n" } },
     {
@@ -241,6 +244,7 @@ test("merge-back resolves merge conflicts with task runner", async () => {
       match:
         "git rev-parse --verify --quiet workflow-2026-03-22-expo-graphql-resolvers",
     },
+    { match: "git rev-parse --verify --quiet MERGE_HEAD", result: { exitCode: 1 } },
     { match: "git status --porcelain=v1" },
     { match: "git rev-parse --abbrev-ref HEAD", result: { stdout: "main\n" } },
     {
@@ -289,6 +293,7 @@ test("merge-back aborts when automatic conflict resolution is declined", async (
       match:
         "git rev-parse --verify --quiet workflow-2026-03-22-expo-graphql-resolvers",
     },
+    { match: "git rev-parse --verify --quiet MERGE_HEAD", result: { exitCode: 1 } },
     { match: "git status --porcelain=v1" },
     { match: "git rev-parse --abbrev-ref HEAD", result: { stdout: "main\n" } },
     {