diff --git a/CLAUDE.md b/CLAUDE.md
index 5720a3a5..d008eafc 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -78,12 +78,21 @@ Tests use **Catch2** and are collected into a single binary `tests/jfjoch_test`.
 ```
 make -j$(nproc) jfjoch_test
 cd tests
-./jfjoch_test                       # all tests
 ./jfjoch_test "<test name>"         # one test case (exact name in TEST_CASE)
+./jfjoch_test "Prefix*"             # by name prefix
 ./jfjoch_test "[tag]"               # by tag
 ./jfjoch_test -r junit -o report.xml
 ```
 
+**Do not run the whole suite** (`./jfjoch_test` with no filter). It takes far too long to be worth
+running locally, and **CI runs it on every push anyway**. Run only the cases or tags covering the
+code you changed and stop there; a bare `./jfjoch_test` is justified only for a genuinely sweeping
+change. The same applies to the 37-crystal rotation battery (`rugnux_vs_xds.py`) — run it when a
+change plausibly moves merged results, not as a reflex.
+
+**Do not `git push`.** Commit when asked; pushing is a separate decision that belongs to the
+maintainer.
+
 `make jfjoch_hdf5_test` builds the HDF5 write-speed benchmark (it lives in `tools/`, so the binary
 is `build/tools/jfjoch_hdf5_test`); CI also uses it to produce files that are validated against XDS
 (Durin/Neggia), DIALS and CrystFEL. `jfjoch_hdf5_enospc_test` + the `enospc_shim` module test