chore: AI-check Exclusions tightening — 2-week advisory review

.ai-checks/branching-and-pr-strategy.md

@@ -108,3 +108,16 @@ a destructive operation and the human must do it.
   confirm it was rebase-merged.
 - Initial repo bootstrap commits (before the rules existed). Use
   judgement on the date of the violation.
+- **GitHub Actions synthetic merge commit.** `actions/checkout@v4`
+  checks out `refs/pull/N/merge` — a two-parent commit GitHub creates
+  for CI with a message of the form `Merge <sha>... into <sha>...`.
+  This commit is NOT part of the PR author's branch; it exists only on
+  the runner. If the only merge-shaped commit you can see is the
+  top-of-tree HEAD with that exact message pattern, the branch is
+  rebased cleanly and you must pass this check. Only flag merge commits
+  that appear *within* the PR's own commit list (i.e. authored before
+  the synthetic HEAD).
+- **Do not infer the source branch from the PR title, description, or
+  diff content.** Read the branch name from explicit metadata (e.g.
+  `head.ref` in the diff context). If that information is absent, do
+  not assume the PR came from `main`.

.ai-checks/comment-discipline.md

@@ -105,3 +105,7 @@ Apply across the diff. Especially noisy areas historically:
 - Tests, where descriptive `# Given / # When / # Then` comments can
   improve readability — judgement call, lean permissive.
 - Generated code / migrations.
+- **Lines removed by this PR.** A line shown in the diff with a `-`
+  prefix is being *deleted*. Do not flag removed lines as violations —
+  they are already gone. Evaluate only lines that are added (`+`
+  prefix) or present in unchanged context.

.ai-checks/env-var-sync.md

@@ -72,3 +72,11 @@ key, even a revoked one. Flag any commit that adds a value matching
 - Internal feature flags that are intentionally undocumented (rare;
   require a comment in code explaining why).
 - Test-only env vars set in `tests/` and never read by production code.
+- **Django model field names, method parameters, and Python attribute
+  names are not environment variables.** Only flag lines where code
+  explicitly reads from the process environment: `os.getenv(...)`,
+  `os.environ[...]`, `os.environ.get(...)`, `settings.RAGTIME_*`, or
+  equivalent runtime env reads. A Django model field named `show_name`
+  has no connection to a hypothetical `RAGTIME_SHOW_NAME` env var — do
+  not invent env var names from field or variable names you see in the
+  diff.

.ai-checks/feature-pr-docs.md

@@ -136,3 +136,7 @@ prompt) satisfies this check; summarized/paraphrased content does not.
 - Bug fixes, refactors, dependency bumps, doc-only PRs.
 - Hot-fixes explicitly tagged as urgent in the PR description (note as
   follow-up debt, don't block).
+- **CI/CD and dev-tooling PRs** — changes confined to `.github/`,
+  `.ai-checks/`, or similar non-runtime infrastructure paths that add
+  no application behaviour. These are tooling/chore changes regardless
+  of their size. Established precedent: PRs #118, #122, #134.

.ai-checks/pipeline-step-sync.md

@@ -81,3 +81,17 @@ must be reflected in the "Pipeline parallelism" paragraph of
   (e.g. renaming an internal helper, extracting a sub-function inside a step).
 - Pure bug fixes inside a step that don't change its contract.
 - Tests-only PRs.
+- **Changes inside an existing step's implementation that do not alter the
+  step list.** If `PIPELINE_STEPS` in `episodes/models.py` is unchanged and
+  no `@DBOS.step()` decorators are added or removed in
+  `episodes/workflows.py`, then any change to the code *inside* a step
+  (new field extracted, LLM prompt adjusted, bug fixed) is not a pipeline
+  structural change. Do not require `README.md`'s high-level step-table to
+  update for per-field or per-behaviour changes within a step.
+- **`doc/README.md` updates that describe per-step behaviour** (fields
+  extracted, edge-case handling, additive-only semantics for a field) are
+  compliant even if the `README.md` summary table is not updated — the table
+  documents step *names and roles*, not per-field implementation details.
+  A PR that updates `doc/README.md` to describe new behaviour inside an
+  existing step, while leaving `README.md`'s table unchanged, passes this
+  check.