feat: surface merge conflicts as PR review-fix items with priority ordering

[itsmiso-ai]

Fixes #355

Summary

Merge-conflicting PRs are invisible to the current worker system. This PR adds a sync/ingestion step that detects open PRs with merge conflicts and creates pr-review-fix items with priority ordering.

Changes

• PrFixType enum: Added MERGE_CONFLICT, CI_FAILURE, REVIEW_FEEDBACK, OTHER types
• PrFixQueueItem.type field: New field to categorize fix items
• Priority ordering: Queue now returns items in priority order: conflicts > CI failures > review feedback
• Merge conflict detection: ingestMergeConflict() function for detecting CONFLICTING PRs
• Idempotent cleanup: clearResolvedConflictItems() clears items when PR becomes mergeable or closed
• Sync route updates: Detects conflicts and clears resolved items during periodic sync
• Queue endpoint: Supports prioritize_by_type parameter (default: true)

Acceptance Criteria

• Dispatch detects open PRs where mergeable=CONFLICTING and creates pr-review-fix items with type: "MERGE_CONFLICT"
• The review-fix queue returns items in priority order: conflicts > CI fails > requested changes
• Workers can distinguish conflict items from review-feedback items via fixType field
• Already-existing conflict items are not re-created on every sync pass (idempotent)
• Conflict items are cleared/marked resolved when the PR becomes mergeable or is closed

Migration

Added migration 20260611000000_add_pr_fix_type to add the PrFixType enum and type field to PrFixQueueItem.

[its-saffron]

AI Automated Review

Full PR review.

Analysis engine: MiniMax-M2.7@https://litellm.jory.dev/v1 (anthropic) — routed smart (risk match: db_or_migration_changes)

Review: PR PR 356 — Surface merge conflicts as PR review-fix items with priority ordering

Recommendation

Approve. The migration is safe, the implementation satisfies all linked issue acceptance criteria, and the code follows repository conventions.

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Change-by-Change Findings

Migration (prisma/migrations/20260611000000_add_pr_fix_type/migration.sql)

• New enum PrFixType with values MERGE_CONFLICT, CI_FAILURE, REVIEW_FEEDBACK, OTHER — standard Prisma pattern, no data loss risk.
• **ADD COLUMN type NOT NULL DEFAULT 'OTHER'** — populates existing rows with the catch-all OTHER` value, which is correct since pre-existing queue items had no explicit type.
• Two composite indexes on (type) and (status, type) for efficient priority-ordered queue queries.

Schema (prisma/schema.prisma)

• Enum PrFixType added; type field on PrFixQueueItem defaults to OTHER.
• Two new indexes mirror the migration SQL.

Code changes (src/lib/pr-followup-ingestion.ts)

• ingestMergeConflict(): detects mergeable=CONFLICTING PRs, enqueues with type: "MERGE_CONFLICT". Correctly checks bot author and repo owner eligibility before enqueueing.
• clearResolvedConflictItems(): marks FIXED when PR becomes mergeable or closed. Guarded by type === "MERGE_CONFLICT" and status === "QUEUED" — idempotent.
• ingestMergeStateEvent(): now sets type based on mergeStateStatus ("dirty"/"conflicting" → MERGE_CONFLICT).
• All existing ingestors (ingestCommentEvent, ingestReviewEvent, ingestCheckRunEvent) now set type explicitly (REVIEW_FEEDBACK, CI_FAILURE).

Queue logic (src/lib/pr-fix-queue.ts)

• normalizePrFixType(): proper normalization with hyphens stripped, uppercase comparison.
• listQueuedPrFixItems(): sorts in-memory by PR_FIX_TYPE_PRIORITY then queuedAt when prioritizeByType !== false.
• toAgentQueueItem(): includes fixType in the returned item — workers can distinguish conflict from feedback items.

API route (src/app/api/pr-fix-queue/queued/route.ts)

• Added prioritize_by_type query param (default true) — mirrors the prioritizeByType option in the library.

Types (src/types/index.ts)

• PrFixType type, normalizePrFixType(), VALID_PR_FIX_TYPES, and PR_FIX_TYPE_PRIORITY constant — consistent with the existing PrFixLane/PrFixStatus pattern in the codebase.

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Required Check Responses

✅ review migration for data loss risk

The migration adds a new enum type and a non-null column with a default value. No existing rows are deleted or modified destructively. PostgreSQL handles ADD COLUMN ... DEFAULT 'OTHER' without a table rewrite in modern versions (11+), so this is a low-risk online migration. Existing PrFixQueueItem rows will receive type = 'OTHER' by default, which is semantically correct.

⚠️ test migration on a copy of production schema

Cannot verify from the PR corpus. There is no evidence of testing on a production-schema copy in the provided diff, PR body, or linked issue. This is a best-practice recommendation for production deployments: run prisma migrate deploy on a staging snapshot before applying to production. The migration itself is straightforward, but schema size and concurrent write patterns during deployment could reveal edge cases not visible in a clean diff.

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Standards Compliance

• ✅ Enum and type patterns follow existing PrFixLane/PrFixStatus conventions
• ✅ Error handling uses error instanceof Error pattern in routes
• ✅ No agent-specific names in generic code (isAllowedBotAuthor uses env-configurable allowlist)
• ✅ HTTP status codes used appropriately in API routes
• ✅ Audit trail entries written via prFixHistory on status changes
• ✅ No hardcoded agent names or repo names — PR_FOLLOWUP_BOT_IDENTITIES and PR_FOLLOWUP_BRANCH_OWNERS are configurable

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Linked Issue Fit (PR 355)

Acceptance Criterion	Status
Dispatch detects mergeable=CONFLICTING and creates pr-review-fix items with type: "MERGE_CONFLICT"	✅ ingestMergeConflict() in sync route
Queue returns items in priority order: conflicts > CI fails > requested changes	✅ PR_FIX_TYPE_PRIORITY + in-memory sort
Workers can distinguish conflict items via fixType field	✅ toAgentQueueItem() surfaces fixType
Already-existing conflict items are not re-created (idempotent)	✅ Evidence-key deduplication + existence check
Conflict items are cleared when PR becomes mergeable or is closed	✅ clearResolvedConflictItems() sets status: "FIXED"

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Unknowns / Needs Verification

1. Production migration testing — recommend verifying the ADD COLUMN NOT NULL DEFAULT step on a production-schema snapshot before deployment, especially if the PrFixQueueItem table is large or sees high write volume.
2. In-memory sort at scale — listQueuedPrFixItems() loads all queued items into memory and sorts in-process. This is acceptable for typical queue sizes but would need pagination or a database-side ORDER BY if the queue grows to thousands of items. No evidence of queue-size stress testing in the corpus.