diff --git a/.github/workflows/pytest-matrix.yml b/.github/workflows/pytest-matrix.yml
index f3fdcba..3abe73a 100644
--- a/.github/workflows/pytest-matrix.yml
+++ b/.github/workflows/pytest-matrix.yml
@@ -7,17 +7,23 @@ name: pytest-matrix
 # original), and the python-version matrix / runner label are identical
 # across every caller today, so nothing needs to be parameterized yet.
 # CODECOV_TOKEN must be available to the caller (secrets: inherit).
+#
+# CALLERS MUST USE THE JOB ID `pytest-matrix`. Copy the stub from
+# workflow-templates/pytest-matrix.yml; do not write your own. The check name
+# GitHub renders is "<caller job id> / <this job's name>", so the caller's job id
+# IS the branch-protection context prefix: name it anything else and that repo
+# emits a check name no other repo emits, which means a bespoke required-check
+# list for it forever. See the README's "Caller job ids" section.
 
 on:
   workflow_call: {}
 
 jobs:
   pytest-matrix:
-    # Job name is a REQUIRED status check on scitex-stats' develop/main
-    # branch protection today (as "pytest-matrix-on-ubuntu-py3.11" etc,
-    # no caller-job prefix). Under workflow_call the check name GitHub
-    # renders is "<caller-job-id> / <this-name>" — branch protection
-    # required-check strings will need updating post-migration (see PR).
+    # This name is the SECOND half of the required status check. The full context
+    # a caller emits is "pytest-matrix / pytest-matrix-on-ubuntu-py3.11" (given the
+    # mandated caller job id above). Renaming this breaks branch protection in
+    # every repo at once — reconcile protection in the same change if you ever do.
     name: pytest-matrix-on-ubuntu-py${{ matrix.python-version }}
     runs-on: [self-hosted, Linux, X64, spartan-cpu]
     timeout-minutes: 30
diff --git a/README.md b/README.md
index d5a6156..3c649fc 100644
--- a/README.md
+++ b/README.md
@@ -9,11 +9,14 @@ Under `.github/workflows/`, called from a leaf repo like:
 
 ```yaml
 jobs:
-  call:
-    uses: scitex-ai/.github/.github/workflows/<name>.yml@main
+  pytest-matrix:   # <-- the job id is load-bearing. See "Caller job ids" below.
+    uses: scitex-ai/.github/.github/workflows/pytest-matrix.yml@main
     secrets: inherit
 ```
 
+Copy the stub from [`workflow-templates/`](workflow-templates/) rather than
+writing one — it also shows up under *Actions → New workflow* in every repo.
+
 - `pytest-matrix.yml` — pytest across the supported Python versions.
 - `import-smoke.yml` — bare-install import smoke test.
 - `quality-audit.yml` — `scitex-dev ecosystem audit-all` quality gate.
@@ -21,6 +24,56 @@ jobs:
 - `cla.yml` — CLA Assistant + owner direct-push bypass.
 - `auto-merge-to-develop.yml` — auto-merge green PRs targeting `develop`.
 
+## Caller job ids — DO NOT INVENT THEM
+
+**The caller's job id is the branch-protection context prefix.** GitHub names the
+status check of a reusable-workflow call:
+
+```
+"<caller job id> / <job name inside the reusable workflow>"
+```
+
+So a repo that calls `pytest-matrix.yml` from a job it named `test` emits
+`test / pytest-matrix-on-ubuntu-py3.11`, while one that named it `pytest-matrix`
+emits `pytest-matrix / pytest-matrix-on-ubuntu-py3.11`. Different repos, different
+required-check names, and **one protection list can no longer serve the ecosystem** —
+every repo needs a bespoke list, hand-read off a real PR, forever.
+
+Use exactly these job ids. They are what the already-migrated repos emit today
+(`scitex-dict`, `scitex-ui`, `scitex-todo`, `scitex-scholar`), so adopting them
+is a no-op for those repos rather than fresh churn:
+
+| reusable workflow | caller job id | resulting status check |
+|---|---|---|
+| `pytest-matrix.yml` | `pytest-matrix` | `pytest-matrix / pytest-matrix-on-ubuntu-py3.{11,12,13}` |
+| `import-smoke.yml` | `import-smoke` | `import-smoke / import-smoke-on-ubuntu-py3-12` |
+| `quality-audit.yml` | `quality-audit` | `quality-audit / audit` |
+| `rtd-sphinx-build.yml` | `docs-sphinx` | `docs-sphinx / docs-sphinx` |
+
+`cla.yml` and `auto-merge-to-develop.yml` are exempt: neither emits a prefixed
+required check (the CLA status is posted by the action as a plain `CLAssistant`
+commit status, and auto-merge gates nothing), so their caller job id is not
+load-bearing.
+
+### Migrating a repo onto these workflows
+
+Adopting a reusable workflow **renames that repo's status checks** (the prefix is
+added). Branch protection must be reconciled in the same change, or the repo goes
+green-but-unmergeable — every check passing, `mergeStateStatus: BLOCKED`, no error
+anywhere.
+
+1. Open the migration PR and let CI run.
+2. **Read the emitted check names off that real PR.** Never guess them.
+3. Compare with `required_status_checks.contexts` on **each** protected branch
+   (`main` *and* `develop` — they drift apart).
+4. Reconcile — *reconcile*, not blanket-flip. Some repos already had protection
+   set to the post-migration names in anticipation, and need no change at all;
+   others still carry the pre-migration names and do.
+
+Note `scitex-dev`: its protection was deliberately set back to the **bare**
+(pre-migration) names as an interim to unblock merges. When it migrates, its
+protection must be flipped **to the prefixed names in the same change**.
+
 PyPI publish/release workflows stay local to each leaf repo — PyPI trusted
 publishing (OIDC) does not support `workflow_call` reusable workflows
 (`invalid-publisher` error), so that job must run in a workflow file that
diff --git a/workflow-templates/pytest-matrix.properties.json b/workflow-templates/pytest-matrix.properties.json
new file mode 100644
index 0000000..66aa160
--- /dev/null
+++ b/workflow-templates/pytest-matrix.properties.json
@@ -0,0 +1,7 @@
+{
+  "name": "SciTeX pytest-matrix (Spartan)",
+  "description": "Canonical caller for the org reusable pytest-matrix workflow. Runs pytest on the self-hosted Spartan runners across py3.11/3.12/3.13. Do not rename the job id — it is the branch-protection context prefix.",
+  "iconName": "octicon check-circle",
+  "categories": ["Continuous integration", "Python"],
+  "filePatterns": ["pyproject.toml$"]
+}
diff --git a/workflow-templates/pytest-matrix.yml b/workflow-templates/pytest-matrix.yml
new file mode 100644
index 0000000..01197f5
--- /dev/null
+++ b/workflow-templates/pytest-matrix.yml
@@ -0,0 +1,38 @@
+name: tests
+
+# CANONICAL CALLER STUB — copy this verbatim. Do not rename the job.
+#
+# The job id `pytest-matrix` is NOT cosmetic. GitHub names the status check of a
+# reusable-workflow call:
+#
+#     "<caller job id> / <job name inside the reusable workflow>"
+#
+# so the job id below IS the branch-protection context prefix. With `pytest-matrix`
+# every repo in the ecosystem emits exactly:
+#
+#     pytest-matrix / pytest-matrix-on-ubuntu-py3.11
+#     pytest-matrix / pytest-matrix-on-ubuntu-py3.12
+#     pytest-matrix / pytest-matrix-on-ubuntu-py3.13
+#
+# One required-status-check list then serves every repo. Rename the job to
+# `test`, `call`, `ci`, … and that repo emits `test / pytest-matrix-on-ubuntu-py3.11`
+# instead — a bespoke protection list for that repo, forever, and a merge that
+# blocks silently until someone hand-reads the new names off a real PR.
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+  schedule:
+    - cron: "0 17 * * *"  # nightly, off-peak
+  workflow_dispatch:
+
+concurrency:
+  group: tests-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  pytest-matrix:            # <-- DO NOT RENAME (see above)
+    uses: scitex-ai/.github/.github/workflows/pytest-matrix.yml@main
+    secrets: inherit