Select the change. If not given, run openspec list --json, show changes that have delta specs under specs/, and let the user choose. Never guess.
Find delta specs at openspec/changes/<name>/specs/*/spec.md. Each may contain ## ADDED Requirements, ## MODIFIED Requirements, ## REMOVED Requirements, ## RENAMED Requirements (FROM:/TO: format). If none found, tell the user and stop.
For each capability with a delta spec, read both the delta and the main spec at openspec/specs/<capability>/spec.md (may not exist yet), then apply intelligently:
- ADDED — add if new; if it already exists, update it to match (treat as an implicit MODIFIED).
- MODIFIED — find the requirement and apply the changes: add scenarios, modify existing ones, or change the description. Preserve content the delta doesn't mention.
- REMOVED — remove the entire requirement block.
- RENAMED — find the FROM requirement, rename to TO.
- If the capability has no main spec yet, create openspec/specs/<capability>/spec.md with a Purpose section (brief, can be TBD) and the ADDED requirements.
Show a summary: which capabilities were updated and what changed (added/modified/removed/renamed requirements).

Key principle: intelligent merging

The delta represents intent, not a wholesale replacement. To add a scenario, include just that scenario under MODIFIED — don't copy existing ones. Use judgment to merge sensibly; the operation should still be idempotent (running it twice gives the same result).

Guardrails

Read both delta and main specs before changing anything.
Preserve existing content the delta doesn't mention.
Ask for clarification if intent is unclear rather than guessing.
Show what's changing as you go.

Completion

Complete when every delta spec found in step 2 has been applied to its main spec (or a new main spec created), the summary lists every capability touched, and re-running the sync on the same inputs would produce no further changes.

openspec-sync-specs

Sync delta specs to main specs

Steps