Problem

internal/merge/merge.go defines its own Issue struct (lines 43-66) that duplicates types.Issue. When fields are added to types.Issue, developers must remember to update the merge driver's copy. This has caused silent data loss:

• fix: merge driver silently drops issue fields (metadata, labels, assignee, etc.) #1480 — Metadata, labels, assignee, and many other fields are dropped during merge

Root Cause: Struct Duplication Drift

Go's JSON unmarshaler ignores unknown fields by default. When types.Issue gained new fields (like Metadata), the merge driver's local struct wasn't updated. Tests passed because they didn't check field preservation, and the compiler didn't complain.

Current State

The merge driver already depends on internal/types:

import "github.com/steveyegge/beads/internal/types"

const (
    StatusTombstone = string(types.StatusTombstone)
    StatusClosed    = string(types.StatusClosed)
)

So "vendored code purity" is not a constraint.

Proposed Fix: Use types.Issue Directly

Refactor internal/merge/merge.go to use types.Issue instead of its local struct.

Changes Required

1. Remove local Issue struct definition
2. Use types.Issue throughout merge logic
3. Handle merge-specific fields:
   • RawLine — Add to types.Issue with json:"-" tag, or use a wrapper struct
   • Time fields — types.Issue uses time.Time, merge uses string (needs adapter)

Wrapper Approach (if needed)

type MergeIssue struct {
    types.Issue
    RawLine string `json:"-"` // Merge-specific: original JSON line for conflict output
}

Alternatives Considered

Recommendation: Option A. The dependency already exists, and this prevents future data loss.

Acceptance Criteria

• internal/merge/merge.go imports and uses types.Issue (or a thin wrapper)
• All fields from types.Issue are preserved during merge
• Existing merge tests pass
• Add test: round-trip an issue with metadata through merge, verify preservation

Related

• fix: merge driver silently drops issue fields (metadata, labels, assignee, etc.) #1480 — Immediate fix: add missing fields manually (triage)
• feat: add optional JSON metadata field to issues #1406 — Metadata feature that exposed this bug