phx-deps-update

name	phx:deps-update
description	Bump outdated Hex deps — inventory, snapshot changelogs, update, fix breaks, split reviewable PRs (patches bundled, majors solo). Use to upgrade/bump Elixir dependencies or when versions fall behind. NOT for deps.get failures (/phx:investigate).
effort	high
argument-hint	[--scope patch|minor|major|all] [--pkg <name>...] [--pr-per major|area|none] [--dry-run]

Dependency Update (Freshness)

Inventory → update → fix breaks → grouped PRs. This is the only MUTATING deps skill: it edits mix.exs, mix.lock, and source. Security scanning stays in /phx:deps-audit; the vet ledger stays in /phx:deps-vet.

Usage

/phx:deps-update                       # inventory + interactive scope pick
/phx:deps-update --scope patch         # bundle all patch bumps, one PR
/phx:deps-update --pkg phoenix_live_view   # one package (+ coupled group)
/phx:deps-update --dry-run             # inventory only, no changes

Iron Laws

1. NEVER cross a major version without an explicit mix.exs edit — mix deps.update stays within requirements. Edit the constraint first; add override: true only when mix hex.outdated <pkg> shows a transitive consumer blocking. One major per PR
2. ALWAYS snapshot the changelog delta BEFORE updating — capture deps/<pkg>/CHANGELOG.md, then delta via mix hex.package diff. Never update blind
3. NEVER claim an update is safe without verification — run /phx:verify (compile --warnings-as-errors + test). "Compiles" ≠ "works"
4. ALWAYS move coupled packages together — Phoenix core, Ecto, Ash, Oban, telemetry families update in the SAME step/commit (see ${CLAUDE_SKILL_DIR}/references/coupled-groups.md)
5. NEVER commit a partial bump — mix.lock + mix.exs edits + (for Phoenix-family) assets/package-lock.json in ONE commit
6. HAND OFF security to /phx:deps-audit — run it on the lock diff before any PR; don't reimplement audit rules
7. hex.outdated exit 1 is normal — it means "deps are outdated", not failure. Capture with || true

Workflow

Phase 0: Discover

Read mix.exs: deps list, umbrella (apps_path:), git/path deps, private orgs (organization:/repo: in tuples), Phoenix/Ash presence. Create scratch dir .claude/deps-update/{YYYY-MM-DD}/.

Phase 1: Inventory

mix hex.outdated --all || true — parse the text table (no JSON exists; see ${CLAUDE_SKILL_DIR}/references/update-mechanics.md). Classify each row patch/minor/major by semver delta; Update not possible = blocked major (mix.exs constraint). Write inventory.md to scratch. Render grouped table: Patch / Minor / Major / Blocked / Git-deps (manual). --dry-run stops here.

Phase 2: Scope (AskUserQuestion)

Present groups with counts and risk. Default recommendation: "Patches (N) — low risk, bundle into one PR". --scope/--pkg flags skip the prompt. When ≥2 members of a coupled group are outdated, force them into one step even under a narrower scope.

Phase 3: Per-Package Update Loop

For each selected package, in coupled-group order:

1. Snapshot deps/<pkg>/CHANGELOG.md → scratch/before/
2. Update — patch/minor: mix deps.update <pkg> [coupled...]; major: edit mix.exs constraint (+ override: true if needed), then mix deps.update <pkg>
3. git diff mix.lock → the REAL {pkg, old, new} set (hex.outdated says what could change; the lock diff says what did)
4. Changelog delta: mix hex.package diff <pkg> <old>..<new> — keep the CHANGELOG hunk. Empty → gh api repos/{o}/{r}/releases fallback → compare-URL note (see ${CLAUDE_SKILL_DIR}/references/changelog-sources.md)
5. Write scratch/{pkg}-{old}-{new}.md
6. Phoenix-family in the diff + assets/package.json exists → npm install --prefix assets, stage assets/package-lock.json with the same commit

Phase 4: Verify

Run /phx:verify. On failure → Phase 5; else Phase 6.

Phase 5: Breaking-Change Fixes

Read the changelog deltas for "breaking"/"removed"/"deprecated" + the compile/test errors. Fix source (apply the sibling-file check). Re-verify.

Phase 6: Security Handoff

Run /phx:deps-audit on the working mix.lock diff (its Mode B default). BLOCK findings → surface and offer /phx:deps-vet <pkg> <ver> for accepted risks. Never skip this before a PR.

Phase 7: Group, Commit, PR

Apply the splitting strategy (${CLAUDE_SKILL_DIR}/references/pr-strategy.md): patches bundled, minors by area, majors solo, coupled groups always together. PR bodies cite the changelog excerpt, the https://diff.hex.pm/diff/<pkg>/<old>..<new> link, verification result, and the deps-audit risk band. Stage lock + mix.exs + package-lock together.

Integration

/phx:deps-update (mutating) → /phx:deps-audit (security, Mode B)
        │                              │ BLOCK → /phx:deps-vet (ledger)
        └→ /phx:verify (gate) → grouped commits / PRs

References

• ${CLAUDE_SKILL_DIR}/references/update-mechanics.md — hex.outdated parsing, update vs unlock+get, majors, lock-diff
• ${CLAUDE_SKILL_DIR}/references/changelog-sources.md — hex.package diff, gh fallbacks, private orgs
• ${CLAUDE_SKILL_DIR}/references/coupled-groups.md — must-move-together groups + edge cases
• ${CLAUDE_SKILL_DIR}/references/pr-strategy.md — grouping rules, area buckets, PR template, scratch layout