renamer/specs/004-extension-rename/data-model.md

Data Model – Extension Command

Entity: ExtensionRequest

• Fields
  • WorkingDir string — Absolute path resolved from CLI --path or current directory.
  • SourceExtensions []string — Ordered list of unique, dot-prefixed source extensions (case-insensitive comparisons).
  • TargetExtension string — Dot-prefixed extension applied verbatim during rename.
  • IncludeDirs bool — Mirrors --include-dirs scope flag.
  • Recursive bool — Mirrors --recursive traversal flag.
  • IncludeHidden bool — True only when --hidden supplied.
  • ExtensionFilter []string — Normalized extension filter from --extensions, applied before source matching.
  • DryRun bool — Indicates preview-only execution (--dry-run).
  • AutoConfirm bool — Captures --yes for non-interactive apply.
  • Timestamp time.Time — Invocation timestamp for ledger correlation.
• Validation Rules
  • Require at least one source extension and one target extension (total args ≥ 2).
  • All extensions MUST start with . and contain ≥1 alphanumeric character after the dot.
  • Deduplicate source extensions case-insensitively; warn on duplicates/no-ops.
  • Target extension MUST NOT be empty and MUST include leading dot.
  • Reject empty string tokens after trimming whitespace.
• Relationships
  • Consumed by the extension rule engine to enumerate candidate files.
  • Serialized into ledger metadata alongside ExtensionSummary.

Entity: ExtensionSummary

• Fields
  • TotalCandidates int — Number of filesystem entries examined post-scope filtering.
  • TotalChanged int — Count of files scheduled for rename (target extension applied).
  • NoChange int — Count of files already matching TargetExtension.
  • PerExtensionCounts map[string]int — Matches per source extension (case-insensitive key).
  • Conflicts []Conflict — Entries describing colliding target paths.
  • Warnings []string — Validation and scope warnings (duplicates, no matches, hidden skipped).
  • PreviewEntries []PreviewEntry — Ordered list of original/new paths with status changed|no_change|skipped.
  • LedgerMetadata map[string]any — Snapshot persisted with ledger entry (sources, target, flags).
• Validation Rules
  • Conflicts list MUST be empty before allowing apply.
  • NoChange + TotalChanged MUST equal count of entries included in preview.
  • Preview entries MUST be deterministic (stable sort by original path).
• Relationships
  • Emitted to preview renderer for CLI output formatting.
  • Persisted with ledger entry for undo operations and audits.

Entity: Conflict

• Fields
  • OriginalPath string — Existing file path causing the collision.
  • ProposedPath string — Target path that clashes with another candidate.
  • Reason string — Short code (e.g., duplicate_target, existing_file) describing conflict type.
• Validation Rules
  • ProposedPath MUST be unique across non-conflicting entries.
  • Reasons limited to known enum for consistent messaging.
• Relationships
  • Referenced within ExtensionSummary.Conflicts.
  • Propagated to CLI preview warnings.

Entity: PreviewEntry

• Fields
  • OriginalPath string
  • ProposedPath string
  • Status string — changed, no_change, or skipped.
  • SourceExtension string — Detected source extension (normalized lowercase).
• Validation Rules
  • Status MUST be one of the defined constants.
  • ProposedPath MUST equal OriginalPath when Status == "no_change".
• Relationships
  • Aggregated into ExtensionSummary.PreviewEntries.
  • Used by preview renderer and ledger writer.