Update changelog to May 2026, convert changelog prompt to skill

- Add changelog entries for February through May 2026
- Move changelog generation instructions from claude_changelog.md to
  .claude/skills/docs-changelog/SKILL.md for auto-discovery
- Gitignore .claude/settings.local.json to keep local permissions private

Author: javier

.claude/skills/docs-changelog/SKILL.md

@@ -0,0 +1,154 @@
+# Documentation changelog
+
+Trigger this skill when documentation changes are significant enough to be
+user-facing. This means: new pages, new sections, new functions or SQL
+keywords, restructured content, updated examples, or corrected technical
+instructions.
+
+Do NOT trigger for: typo fixes, whitespace/formatting, alphabetical
+reordering, sidebar-only changes, internal link updates, CI/build config,
+or README updates.
+
+## When to update the changelog
+
+After completing a documentation task, evaluate whether the changes are
+changelog-worthy. If yes, update `documentation/changelog.mdx` as part of the
+same work, before reporting the task as done.
+
+## How to generate a changelog entry
+
+### Step 1: Determine the date range
+
+1. Read `documentation/changelog.mdx` and find the most recent month header
+   (format: `## Month YYYY`).
+2. If the changelog does not exist or has no date, use 1 month ago. No
+   exceptions.
+3. Store this as `SINCE_DATE`.
+4. Never go further back than the calculated date without user confirmation.
+
+### Step 2: Get commits since that date
+
+```bash
+git log --since="$SINCE_DATE" --pretty=format:"%H|%ad|%s" --date=short --no-merges -- documentation/
+```
+
+### Step 3: Get QuestDB releases for the period
+
+```bash
+gh api repos/questdb/questdb/releases --jq '.[] | "\(.tag_name)|\(.published_at)"'
+```
+
+Filter to releases within the period. Format:
+
+```markdown
+### Releases
+
+- [9.3.2](https://questdb.com/release-notes/) - Released January 28, 2026
+- [9.3.1](https://questdb.com/release-notes/) - Released January 14, 2026
+```
+
+Rules:
+- One line per release, descending order (newest first)
+- Link text is the version number
+- All links point to `https://questdb.com/release-notes/`
+- Date format: "Released Month DD, YYYY"
+- Place "Releases" FIRST in each month (before New, Updated, etc.)
+- Omit if no releases that month
+
+### Step 4: Analyze each commit
+
+For each commit hash, check the diff:
+
+```bash
+git show <hash> --stat --no-color -- '*.md' '*.mdx'
+```
+
+Read the full diff when the stat is ambiguous:
+
+```bash
+git diff <hash>^..<hash> -- '*.md' '*.mdx'
+```
+
+**SKIP (cosmetic/internal):**
+- Typo fixes (fewer than 5 words changed)
+- Whitespace/formatting only
+- Navigation/sidebar changes only
+- Internal link updates
+- CI/build config changes
+- README updates (unless user-facing)
+- Alphabetical reordering of existing content
+
+**INCLUDE (user-facing):**
+- New documentation pages
+- New sections in existing pages
+- Updated code examples
+- API reference changes
+- New SQL function docs
+- Configuration option docs
+- Tutorial additions/updates
+- Corrected technical instructions
+
+### Step 5: Categorize changes
+
+Group into:
+- **Releases** - QuestDB releases in the period (from Step 3)
+- **New** - Brand new pages or major new sections (content that did not exist before)
+- **Updated** - Significant updates to existing content (restructured pages, rewritten sections, new examples)
+- **Reference** - Individual functions, parameters, config properties, or syntax additions to existing reference pages
+- **Guides** - Tutorials, how-tos, walkthroughs
+
+### Step 6: Generate the entry
+
+Format as Docusaurus-compatible MDX, one `## Month YYYY` header per month:
+
+```mdx
+## February 2026
+
+### Releases
+
+- [9.4.0](https://questdb.com/release-notes/) - Released February 15, 2026
+
+### New
+
+- [TICK Syntax](/docs/query/operators/tick/) - New DSL for expressing complex time intervals
+- [Database Views](/docs/concepts/views/) - Virtual tables for query composition
+
+### Updated
+
+- [Materialized Views](/docs/concepts/materialized-views/) - Added `REFRESH PERIOD` compact syntax
+
+### Reference
+
+- Added `weighted_avg()`, `weighted_stddev_rel()`, `weighted_stddev_freq()` functions
+```
+
+### Step 7: Validate links BEFORE writing
+
+Before generating any internal link, verify the target file exists:
+
+```bash
+ls documentation/path/to/page.md 2>/dev/null || echo "NOT FOUND"
+```
+
+If a file does not exist, describe the change without a link:
+- "Added TICK syntax documentation for time intervals"
+
+Never generate a markdown link to a path you have not confirmed exists.
+
+Do NOT run `yarn build` to validate links during iteration. Check the
+filesystem directly. Only run a build check once at the end if needed.
+
+### Step 8: Update the changelog file
+
+Prepend the new entry after the frontmatter and intro paragraph but before
+existing month entries.
+
+The changelog file is `documentation/changelog.mdx` (NOT
+`documentation/docs/changelog.mdx`).
+
+## Writing style
+
+- Focus on what users can now learn or do, not which file was modified.
+- One line per change, concise.
+- Link to the page when the link is verified; otherwise describe without linking.
+- Use sentence case for descriptions.

.gitignore

@@ -24,6 +24,9 @@ all_queries.sql
 failed_queries.sql
 query_validation_report.txt
 
+# Claude Code local settings (personal permissions, not shared)
+.claude/settings.local.json
+
 # Misc
 .DS_Store
 .env.local