jr: implement Gerrit-style conflict handling

- Add RetryContext to track failed attempts (merge conflicts,
rejections) - jr review checks for clean cherry-pick before showing
diff - If conflict detected, kicks back to coder with context -
Worker prompt includes retry context (attempt count, conflict files,
reason) - After 3 failed attempts, marks task for human intervention

Task-Id: t-1o2g8gudqlx

1 files changed, 106 insertions, 19 deletions

diff --git a/Omni/Jr.hs b/Omni/Jr.hs
index bae5588..0cf22f6 100644
--- a/Omni/Jr.hs
+++ b/Omni/Jr.hs
@@ -4,6 +4,7 @@
 
 -- : out jr
 -- : dep sqlite-simple
+-- : dep sqids
 module Omni.Jr where
 
 import Alpha
@@ -143,26 +144,112 @@ reviewTask tid = do
             (x : _) -> x
             [] -> ""
 
-      putText "\n=== Diff for this task ===\n"
-      _ <- Process.rawSystem "git" ["show", commitSha]
-
-      putText "\n[a]ccept / [r]eject / [s]kip? "
-      IO.hFlush IO.stdout
-      choice <- getLine
-
-      case Text.toLower choice of
-        c
-          | "a" `Text.isPrefixOf` c -> do
-              TaskCore.updateTaskStatus tid TaskCore.Done []
-              putText ("Task " <> tid <> " marked as Done.")
-          | "r" `Text.isPrefixOf` c -> do
-              putText "Enter rejection reason: "
-              IO.hFlush IO.stdout
-              reason <- getLine
+      -- Check for merge conflicts before showing diff
+      conflictResult <- checkMergeConflict commitSha
+      case conflictResult of
+        Just conflictFiles -> do
+          putText "\n=== MERGE CONFLICT DETECTED ==="
+          putText "This commit cannot be cleanly applied to live."
+          putText "Conflicting files:"
+          traverse_ (\f -> putText ("  - " <> f)) conflictFiles
+          putText ""
+          putText "Kicking back to coder with context..."
+
+          -- Get current retry count
+          maybeCtx <- TaskCore.getRetryContext tid
+          let attempt = maybe 1 (\c -> TaskCore.retryAttempt c + 1) maybeCtx
+
+          if attempt > 3
+            then do
+              putText "\nTask has failed 3 times. Marking as NeedsHuman."
+              -- For now, just mark as Open with a note (no NeedsHuman status yet)
+              TaskCore.updateTaskStatus tid TaskCore.Open []
+              putText ("Task " <> tid <> " needs human intervention (3 failed attempts).")
+            else do
+              -- Save retry context
+              TaskCore.setRetryContext
+                TaskCore.RetryContext
+                  { TaskCore.retryTaskId = tid,
+                    TaskCore.retryOriginalCommit = Text.pack commitSha,
+                    TaskCore.retryConflictFiles = conflictFiles,
+                    TaskCore.retryAttempt = attempt,
+                    TaskCore.retryReason = "merge_conflict"
+                  }
               TaskCore.updateTaskStatus tid TaskCore.Open []
-              putText ("Task " <> tid <> " reopened.")
-              putText ("Reason: " <> reason)
-          | otherwise -> putText "Skipped; no status change."
+              putText ("Task " <> tid <> " returned to queue (attempt " <> tshow attempt <> "/3).")
+        Nothing -> do
+          -- No conflict, proceed with normal review
+          putText "\n=== Diff for this task ===\n"
+          _ <- Process.rawSystem "git" ["show", commitSha]
+
+          putText "\n[a]ccept / [r]eject / [s]kip? "
+          IO.hFlush IO.stdout
+          choice <- getLine
+
+          case Text.toLower choice of
+            c
+              | "a" `Text.isPrefixOf` c -> do
+                  TaskCore.clearRetryContext tid
+                  TaskCore.updateTaskStatus tid TaskCore.Done []
+                  putText ("Task " <> tid <> " marked as Done.")
+              | "r" `Text.isPrefixOf` c -> do
+                  putText "Enter rejection reason: "
+                  IO.hFlush IO.stdout
+                  reason <- getLine
+                  -- Save rejection as retry context
+                  maybeCtx <- TaskCore.getRetryContext tid
+                  let attempt = maybe 1 (\ctx -> TaskCore.retryAttempt ctx + 1) maybeCtx
+                  TaskCore.setRetryContext
+                    TaskCore.RetryContext
+                      { TaskCore.retryTaskId = tid,
+                        TaskCore.retryOriginalCommit = Text.pack commitSha,
+                        TaskCore.retryConflictFiles = [],
+                        TaskCore.retryAttempt = attempt,
+                        TaskCore.retryReason = "rejected: " <> reason
+                      }
+                  TaskCore.updateTaskStatus tid TaskCore.Open []
+                  putText ("Task " <> tid <> " reopened (attempt " <> tshow attempt <> "/3).")
+              | otherwise -> putText "Skipped; no status change."
+
+-- | Check if a commit can be cleanly cherry-picked onto live
+-- Returns Nothing if clean, Just [conflicting files] if conflict
+checkMergeConflict :: String -> IO (Maybe [Text])
+checkMergeConflict commitSha = do
+  -- Save current state
+  (_, _, _) <- Process.readProcessWithExitCode "git" ["branch", "--show-current"] ""
+  (_, origHead, _) <- Process.readProcessWithExitCode "git" ["rev-parse", "HEAD"] ""
+
+  -- Try cherry-pick
+  (cpCode, _, cpErr) <-
+    Process.readProcessWithExitCode
+      "git"
+      ["cherry-pick", "--no-commit", commitSha]
+      ""
+
+  -- Always abort/reset regardless of result
+  _ <- Process.readProcessWithExitCode "git" ["cherry-pick", "--abort"] ""
+  _ <- Process.readProcessWithExitCode "git" ["reset", "--hard", List.head (List.lines origHead)] ""
+
+  case cpCode of
+    Exit.ExitSuccess -> pure Nothing
+    Exit.ExitFailure _ -> do
+      -- Parse conflict files from error message
+      let errLines = Text.lines (Text.pack cpErr)
+          conflictLines = filter (Text.isPrefixOf "CONFLICT") errLines
+          -- Extract file names (rough parsing)
+          files = mapMaybe extractConflictFile conflictLines
+      pure (Just (if null files then ["(unknown files)"] else files))
+
+extractConflictFile :: Text -> Maybe Text
+extractConflictFile line =
+  -- CONFLICT (content): Merge conflict in path/to/file.hs
+  case Text.breakOn "Merge conflict in " line of
+    (_, rest)
+      | not (Text.null rest) -> Just (Text.strip (Text.drop 18 rest))
+    _ -> case Text.breakOn "in " line of
+      (_, rest)
+        | not (Text.null rest) -> Just (Text.strip (Text.drop 3 rest))
+      _ -> Nothing
 
 test :: Test.Tree
 test =