TODO.md

@@ -21,6 +21,12 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-10-04: Rewrote the note under the canonical Go `make test` example in
+  `REPO_POLICIES.md` (issue 77), which still named the cache-busting build
+  argument that `--no-cache` replaced. It now says where Go's test result cache
+  can replay a pass: on a developer's machine, where the Makefile target runs,
+  and not in the `test` phase of the `Dockerfile`, whose base image and earlier
+  steps hold no result for the repo's tests.
 - 2026-10-04: The Makefile examples in the Go styleguide and the HTTP server
   conventions now fall back to `dev` when `git describe` prints nothing (outside
   a git checkout, or where git is missing or refuses the checkout), instead of

prompts/REPO_POLICIES.md

@@ -317,17 +317,19 @@ style conventions are in separate documents:
     ```
 
     `-count=1` is required on both invocations: it defeats Go's test _result_
-    cache, so the target cannot report a pass it did not earn, and the rerun
+    cache, so neither run can report a stored pass in place of running the
-    reproduces a failure instead of replaying it. It leaves the build cache
+    tests. It leaves the build cache alone, so it costs the runtime of the suite
-    alone, so it costs the runtime of the suite and no recompilation.
+    and no recompilation.
 
-    Note that this is a second, independent cache, stacked below the Docker
+    That cache is Go's own, separate from Docker's layer cache. Go stores a
-    layer cache that [issue #26](https://git.eeqj.de/sneak/prompts/issues/26)
+    passing result in its cache directory (`GOCACHE`), and when the same tests
-    addresses. `CHECK_EPOCH` guarantees the `RUN make test` _step_ re-executes;
+    run again on unchanged code it prints that result, marked `(cached)`,
-    it does not guarantee `go test` inside that step does any work, because the
+    without running them. That matters on a developer's machine, where this
-    `GOCACHE` baked into earlier image layers survives into the re-executed
+    target runs and the directory lasts from one run to the next. The `test`
-    step. They are two separate defects requiring two separate fixes, and a fix
+    phase of the `Dockerfile` needs no `-count=1`: its base image holds no
-    for one must not be recorded as covering the other.
+    result for this repo's tests and nothing before its `go test` step runs a
+    test, so there is nothing to replay. `--no-cache` (above) is what makes that
+    step run on an unchanged tree.
 
     Python example: