Re-pin the refreshed homepage subtitle through the deploy contract and fail drift in Django CI

Grooming decision

Filed as a new issue rather than a #179 amendment. The introducing change is the owner's direct-to-main d8d5f27 ("Refresh homepage copy", 2026-08-18), which postdates #179's contract work — 8424b2c (2026-08-17) had already moved the then-current subtitle through the smoke pin and warned about exactly this miss class. #179 also remains held open by an unrelated [human] item (member-story placeholder copy) that this fix cannot discharge, and the durable guard below is new scope. This fix discharges the deploy side of #179's deploy/smoke.py acceptance criterion; #179's acceptance verifies it there.

Problem

The deploy job of run 32226341286 (main CI on b487b1f, the #196 merge push) failed at "Promote or roll back one atomic web-and-worker release" with release failed safely: home page lacks expected content: Free, project-based courses where you learn to build and build to learn. Every other job was green (playwright, django, quality, container, ci-gate, auto-capture-prior, publish) — only the deploy contract failed.

Root cause (verified): deploy/smoke.py run_http_smoke expects three home strings; the first two are current, but the third (line 192) still pins the pre-refresh subtitle. d8d5f27 changed templates/core/home.html's hero-lede to Free, hands-on courses in data and AI, with a clear path, practical work, and a community to help you get unstuck. and updated core/tests/test_homepage.py, but missed the smoke pin — the second instance of the miss class 8424b2c's message warns about. The Django suite cannot catch this class: core/tests/test_deployment_release.py (~line 2686) feeds run_http_smoke synthetic response bodies, so template↔contract drift is invisible until a live deploy.

The failure predates #196 (d8d5f27 is an ancestor of #196's frozen base 397bcd7; #196 changed one spec file only) — the push merely exposed it. This blocks the green push run #193's landing criteria expect.

Grep-verified: the only live pins of the old subtitle are deploy/smoke.py:192 and core/tests/test_deployment_release.py:2690 (other hits are a stale snapshot under .claude/worktrees/, out of scope). HOME_IDENTITY_MARKER (deploy/smoke.py:30) and the title pin are already the refreshed copy.

Scope

• Update the third expected home string in deploy/smoke.py run_http_smoke to the current hero-lede rendered by templates/core/home.html (exact sentence or opening words is engineering's call; the guard below keeps whichever form in lockstep with the template).
• Update the synthetic passing-home body in core/tests/test_deployment_release.py (~line 2690) to serve the new subtitle, so the happy path exercises the new pin, and re-pin that file's sha256 in _docs/compatibility/development-terminology-allowlist.json (the 8424b2c precedent).
• Add the durable guard: a focused Django test that imports the home-page content strings run_http_smoke pins — title, HOME_IDENTITY_MARKER, and the subtitle — from deploy.smoke (single source of truth; extract a module-level tuple if that keeps it honest) and asserts each appears in the Django-rendered / response, and that the adopted course-discovery lede (Learn data skills. For free. Together.) stays absent from it. Template↔contract drift then fails Django CI instead of the deploy job. test_deployment_release.py already imports deploy.smoke, so importability in the Django suite is proven.

Non-goals

• No template or copy change: d8d5f27's copy is the intended content; the contract follows the template, not the reverse.
• No change to the rest of the release contract (health, version footer, canonical, /unified/, /courses checks) or to the synthetic-body testing approach beyond the string update.
• No Playwright changes (playwright was green on b487b1f).
• No reopening of #179's design work or its member-stories human item.

Acceptance criteria

• run_http_smoke's home content pins (title, HOME_IDENTITY_MARKER, subtitle) all match the current rendered homepage; the old subtitle pin is gone from deploy/smoke.py.
• The synthetic passing-home body in core/tests/test_deployment_release.py contains the new subtitle; the file's terminology-allowlist sha256 is re-pinned and make terminology-check is green.
• The new Django guard test sources the pinned strings from deploy.smoke (not re-typed literals), asserts each appears in the rendered / response and the course-discovery lede stays absent, and passes at head.
• Focused Django tests, make test-ci, lint, format-check, and typecheck green; verification plan per _docs/ci/change-selective-ci.md with all component dispositions recorded.
• Screenshots: not_applicable — no product-page render change (the template is untouched), per _docs/PROCESS.md.

Landing expectation: on-call observes the next main push promote successfully through the deploy job; that green run is also what #193's landing criteria await.

Dependencies: none. Unblocks #193's landing (green push run); discharges the deploy side of #179's smoke criterion.

Normative references: _docs/PROCESS.md (red pipeline attribution), _docs/ci/change-selective-ci.md, _docs/specs/02-url-link-seo-compatibility.md (home canonical/title contract).

Start with deploy/smoke.py and run_http_smoke, then inspect the synthetic homepage body in core/tests/test_deployment_release.py and the rendered response used by the Django homepage tests. Trace the pinned title, identity marker, and subtitle into the homepage response, and follow the terminology allowlist and CI verification references. Done means the contract and fixture match the template, the focused drift guard passes, and the specified checks are green.