diff --git a/TODO.md b/TODO.md
index ad4785c..02562bc 100644
--- a/TODO.md
+++ b/TODO.md
@@ -21,6 +21,10 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-10-04: `REPO_POLICIES.md` now says how a Go tool a repo needs on the host
+  is pinned (issue 37): installed with `go install` pinned to a commit hash,
+  never tracked as a `go.mod` tool dependency or through a `tools.go` file.
+  golangci-lint is unaffected, since no repo installs it on the host.
 - 2026-10-04: The canonical `.gitignore` and `.dockerignore` now also keep out
   `id_ecdsa_sk` and `id_ed25519_sk`, the private key files `ssh-keygen` writes
   for keys backed by a hardware security key (issue 81). Their `.pub` halves
diff --git a/prompts/REPO_POLICIES.md b/prompts/REPO_POLICIES.md
index af0ea80..c66b459 100644
--- a/prompts/REPO_POLICIES.md
+++ b/prompts/REPO_POLICIES.md
@@ -495,6 +495,11 @@ style conventions are in separate documents:
 
     Keep it POSIX sh: no arrays, no `[[`, no `grep -P`.
 
+    A Go tool a repo needs on the host is installed with `go install` pinned to
+    a commit hash (`go install <package>@<commit hash>`). It is never tracked as
+    a `go.mod` tool dependency or through a `tools.go` file, either of which
+    pulls the tool's own dependencies into the repo's `go.mod` and `go.sum`.
+
 - When pinning images or packages by hash, add a comment above the reference
   with the version and date (YYYY-MM-DD).