feat: add draft template for user-facing CHANGELOG.md entries

.opencode/command/changelog.md

@@ -0,0 +1,39 @@
+---
+description: Draft user-facing CHANGELOG.md entries for [Unreleased]
+agent: build
+---
+
+You are updating @CHANGELOG.md.
+
+Goal: write user-facing bullet points for the `## [Unreleased]` section that summarize the changes since the latest git tag up to `HEAD`.
+
+Style rules:
+- Match the writing style of the existing changelog (tone + level of detail).
+- User-facing and benefit-oriented; avoid internal component names unless users see them (ex: “VS Code extension”, “Desktop app”, “Web app”).
+- Prefer 5–9 bullets; group by platform only if it reads better.
+- No new release header; only update the `[Unreleased]` bullets.
+- Don’t include implementation notes, commit hashes, or file paths in the changelog text.
+
+Determine the base version:
+- Use the latest tag (ex: `v1.3.2`) as the base.
+- Inspect all commits after the base up to `HEAD`.
+
+Repo context for style:
+!`BASE=$(git describe --tags --abbrev=0 2>/dev/null || git rev-list --max-parents=0 HEAD); echo "Base: $BASE"; echo; sed -n 1,140p CHANGELOG.md`
+
+Latest tag and commit context:
+!`BASE=$(git describe --tags --abbrev=0 2>/dev/null || git rev-list --max-parents=0 HEAD); COMMIT_COUNT=$(git rev-list --count "$BASE"..HEAD); DIFF=$(git diff --shortstat "$BASE"..HEAD); echo "Base: $BASE | Commit count: $COMMIT_COUNT | Diff: $DIFF"`
+
+Top commits (newest first):
+!`BASE=$(git describe --tags --abbrev=0 2>/dev/null || git rev-list --max-parents=0 HEAD); git log --oneline -30 "$BASE"..HEAD`
+
+Changed files summary:
+!`BASE=$(git describe --tags --abbrev=0 2>/dev/null || git rev-list --max-parents=0 HEAD); git diff --stat "$BASE"..HEAD`
+
+Additional hints (optional, use only if needed):
+- If there are breaking changes or user-visible behavior changes, call them out first.
+- If changes are mostly internal refactors, summarize them as reliability/performance improvements.
+
+Now:
+1) Propose the new `[Unreleased]` bullet list.
+2) Apply it to @CHANGELOG.md (only that section).