[johnnyt]

What

• ex_quality dev dependency: ~> 0.15 to ~> 0.16; mix.lock resolves 0.16.0 from Hex (dev only, no runtime requirement moves).
• .quality.exs: readme: [enabled: :auto, severity: :error], with a comment saying what the stage checks and that findings fail the gate; the header comment lists the stage.
• mix.exs: docs/reference/ast.md joins the package files: (it was already a docs extra in the Reference group).
• README.md: the AST reference link is relative, like its siblings.
• CLAUDE.md: the stated floor reads ~> 0.16.

No lib/ change; no version bump, tag or publish. No changelog fragment: quality gate and documentation only, as the earlier commit that added the analysing-expressions guide to the package files did.

Checks

• Full mix quality is green on the committed tree: the README stage runs at error ("114 lines, every part present", under the 250-line ceiling in .claude/diataxis.md), Doc links checks 58 links, 3,043 tests pass. The commit was made from the tree the second green run covered, with the gate lock and a machine slot held throughout.
• Mutation check: removing the files: entry for docs/reference/ast.md turns Doc links red (readme_not_packaged for the README link at line 81); the file was restored byte-equal and the gate re-run green.
• Firewall: the planning-id and hard-pattern diff scan is clean against origin/main.

Direction check

Each claim was verified on main at c862342: the old floor was ~> 0.15 in mix.exs (the deps list) and in the CLAUDE.md "When a stage fails" paragraph; .quality.exs had no readme key; docs/reference/ast.md was in docs() extras and the Reference group but not in package() files; the README linked it by absolute URL. The stage's check list comes from the ex_quality 0.16.0 README stage, as observed in the gate output. The mix.exs package comment (README-linked files must be in both files: and extras) holds for the new entry.

Provenance

• Prose that stated the old floor: CLAUDE.md only. docs/contributing.md describes the gate without naming stages or a floor; the plan documents under docs/plans/ are dated history and left alone.
• Review: in-turn round on the diff, no findings rejected.

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