kandev/docs/plans/message-queue-merge/task-01-backend-repository.md

id, title, status, wave, depends_on, plan, spec

id	title	status	wave	depends_on	plan	spec
message-queue-merge-01	Backend repository merge	completed	1	None	plan.md	../../specs/ui/message-queue-merge.md

Task 01: Backend repository merge

Acceptance

1. Repository.MergeIntoAbove(ctx, sessionID, sourceID, queuedBy) is defined in internal/orchestrator/messagequeue/repository.go and implemented in both repository_sqlite.go (single transaction) and repository_memory.go, with ErrNoMergeTarget and MetadataSenderTaskID added to types.go.
2. The same-sender-kind rules hold: user merges only into a user entry owned by the caller; agent merges only into an agent entry with the identical sender_task_id; everything else (head, workflow/server/system, mismatched kind, in-flight reserved target) returns ErrNoMergeTarget; a drained source returns ErrEntryNotFound.
3. Merged entry keeps the target's identity (id/position/queued_by/queued_at); content joins with \n\n (no leading blank line when the target content is empty), attachments concatenate, entity_references metadata is the ref-deduplicated union; the source row is deleted; ordering of remaining entries is preserved.

Verification

• cd apps/backend && go test -race ./internal/orchestrator/messagequeue/...

Files

• apps/backend/internal/orchestrator/messagequeue/types.go
• apps/backend/internal/orchestrator/messagequeue/repository.go
• apps/backend/internal/orchestrator/messagequeue/repository_sqlite.go
• apps/backend/internal/orchestrator/messagequeue/repository_memory.go
• apps/backend/internal/orchestrator/messagequeue/repository_sqlite_merge_test.go
• apps/backend/internal/orchestrator/messagequeue/service_test.go

Inputs

• Spec sections: API surface, Data model, Permissions, Failure modes, Scenarios (all merge scenarios).
• Plan sections: Backend → Message-queue package, Tests (repository rows).
• Pattern to mirror: UpdateContentAndMetadata guard + tx in repository_sqlite.go:691; append/applyMetadataUpdates helpers; the memory repo's locking style.

Risks

• Function size/complexity limits (≤80 lines, ≤50 statements, complexity ≤15) — extract the kind gate and the reference-union into helpers.
• goconst: reuse a new MetadataSenderTaskID constant for "sender_task_id".
• Reserved lifecycle rows: a reserved-in-flight target must be rejected, never merged into.