Keep each submodule's git config out of the build context (closes #75)

The canonical `.dockerignore` kept out `.git/config`, which can hold a credential, but not the `config` in each submodule's git directory under `.git/modules/`, nested again for a submodule's own submodules. It now also lists `.git/modules/**/config`, with one sentence in the comment above; `prompts/REPO_POLICIES.md` and both checklists say so in the same words.

The pattern stays under `.git/modules/` because `.git/**/config` would also drop a branch or tag named `config`, which `git describe` may need.

Known gap: a submodule whose name has a `config` path segment loses its whole git directory, so Go's version stamping fails the build loudly; tracked separately.

Model: opus-5-5

.dockerignore

@@ -17,7 +17,10 @@
 # stage that compiles runs `git describe --tags --always` on .git, which
 # does not need .git/config; that file can hold a credential, such as a
 # password in a remote URL or the token the CI checkout step stores there.
+# Each submodule keeps a config with the same exposure in its git directory
+# under .git/modules/, nested again for a submodule's own submodules.
 .git/config
+.git/modules/**/config
 
 # Agent scratch: one full checkout of the repo per in-flight agent.
 # Anchored because it occurs once where agents run at the repo root.

.gitignore

@@ -20,8 +20,26 @@ Thumbs.db
 # Node
 node_modules/
 
-# Environment / secrets
-.env
-.env.*
-*.pem
-*.key
+# Secrets. Unanchored like every entry above, so each matches at every
+# depth. Matching is case-sensitive on Linux, so names use character
+# ranges rather than a lowercase form that misses `Server.Key`.
+
+# Environment files. `*.env` covers bare `.env` and the `prod.env`
+# convention. Only the templates `example.env` and `sample.env` are
+# re-included below. A repository that commits any other template adds
+# its own negation after these lines, for example `!.env.example`.
+*.[eE][nN][vV]
+.[eE][nN][vV].*
+.[eE][nN][vV][rR][cC]
+!example.env
+!sample.env
+
+# Private keys and the bundles carrying them.
+*.[pP][eE][mM]
+*.[kK][eE][yY]
+*.[pP]12
+*.[pP][fF][xX]
+[iI][dD]_[rR][sS][aA]
+[iI][dD]_[dD][sS][aA]
+[iI][dD]_[eE][cC][dD][sS][aA]
+[iI][dD]_[eE][dD]25519

TODO.md

@@ -21,6 +21,19 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-10-04: The canonical `.dockerignore` now also keeps out each submodule's
+  `config` (issue 75). A submodule's git directory lives under `.git/modules/`,
+  nested again for its own submodules, and its `config` can hold a credential
+  just like `.git/config`. The pattern `.git/modules/**/config` covers every
+  depth and leaves the top-level `.git` that `git describe` reads untouched.
+  `REPO_POLICIES.md` and both checklists say so in the same words.
+- 2026-10-03: Fixed two defects in the canonical Go `Dockerfile` example (issue
+  73). The test phase now uses the Debian Go image, since `-race` needs cgo and
+  the alpine image has no C compiler, so the phase failed before running a test.
+  The stage that compiles runs `git config --system --add safe.directory /src`,
+  because a context sent as a tar stream keeps the sender's file owners and git
+  refuses that checkout, leaving the version empty. Both checklists state that
+  step in the same words.
 - 2026-10-03: Moved the canonical golangci-lint to v2.14.0, built with go1.27,
   because v2.12.2 refuses to lint a module whose `go` directive is 1.27 (issue
   65). Releases from v2.13.0 deprecate `exhaustruct` in favour of
@@ -28,6 +41,11 @@ fmt-check, and commit.
   `.golangci.yml` now disables `exhaustruct_v5` beside `exhaustruct`. v2.12.2
   rejects that file, so `REPO_POLICIES.md` and both repo checklists now say a
   repo sets the lint phase digest and re-vendors `.golangci.yml` in one commit.
+- 2026-10-03: Brought the canonical `.gitignore` level with `.dockerignore` on
+  secrets (issue 38): it now also ignores `prod.env`-style `*.env` files,
+  `.envrc`, `*.p12`, `*.pfx` and the extensionless SSH private keys, written to
+  `.gitignore`'s own rules (no `**/` prefix) and case-folded with character
+  ranges. `example.env` and `sample.env` stay trackable through negations.
 - 2026-10-02: The image version now comes from git inside the build (issues 69
   and 71), superseding the 2026-09-08 entry that excluded `.git`. The canonical
   `.dockerignore` sends `.git` but keeps out `.git/config`, which can hold a

prompts/EXISTING_REPO_CHECKLIST.md

@@ -1,6 +1,6 @@
 ---
 title: Existing Repo Checklist
-last_modified: 2026-10-03
+last_modified: 2026-10-04
 ---
 
 Use this checklist when beginning work in a repo that may not yet conform to our
@@ -59,22 +59,28 @@ with your task.
       here run anywhere other than the repo root, the anchored entry misses
       `services/api/.claude/`: add anchored entries for those directories.
 - [ ] If the repo embeds a version in a binary: `.dockerignore` lets `.git` into
-      the build context. It keeps out `.git/config`, which `git describe` does
-      not need and which can hold a credential: a password in a remote URL, or
-      the token the CI checkout step stores there. The stage that compiles has
-      `git` (the Debian Go image has it; an alpine one needs
-      `apk add --no-cache git`) and takes the version from the `VERSION` build
-      argument when one is given, otherwise from `git describe --tags --always`.
-      That gives the tag on a tagged commit; on a later commit, the tag, the
-      number of commits since it and the short commit (`v1.2.3-4-gabc1234`); and
-      the short commit when no tag is reachable. `ARG VERSION` has no default,
-      and the build fails if the context carries `.git` and the version still
-      comes out empty, `dev` or `unknown`. A plain `docker build .` with no
-      build arguments must succeed; a Dockerfile that refuses an empty build
-      argument drops that refusal and keeps the argument. `script/docker` and
-      `script/cibuild` pass the version they compute on the host; it takes
-      precedence. A tag-derived version additionally needs `fetch-depth: 0` on
-      the CI checkout step, which clones shallow and fetches no tags by default.
+      the build context. It keeps out `.git/config` and each submodule's
+      `config` under `.git/modules/` at any depth (`.git/modules/**/config`),
+      which `git describe` does not need and which can hold a credential: a
+      password in a remote URL, or the token the CI checkout step stores there.
+      The stage that compiles has `git` (the Debian Go image has it; an alpine
+      one needs `apk add --no-cache git`) and takes the version from the
+      `VERSION` build argument when one is given, otherwise from
+      `git describe --tags --always`. That gives the tag on a tagged commit; on
+      a later commit, the tag, the number of commits since it and the short
+      commit (`v1.2.3-4-gabc1234`); and the short commit when no tag is
+      reachable. The stage that compiles also marks its working directory safe
+      for git (`git config --system --add safe.directory /src`): a context sent
+      as a tar stream keeps the sender's file owners, and git refuses a checkout
+      owned by another user, so the version would come out empty. `ARG VERSION`
+      has no default, and the build fails if the context carries `.git` and the
+      version still comes out empty, `dev` or `unknown`. A plain
+      `docker build .` with no build arguments must succeed; a Dockerfile that
+      refuses an empty build argument drops that refusal and keeps the argument.
+      `script/docker` and `script/cibuild` pass the version they compute on the
+      host; it takes precedence. A tag-derived version additionally needs
+      `fetch-depth: 0` on the CI checkout step, which clones shallow and fetches
+      no tags by default.
 - [ ] Gitea Actions workflow in `.gitea/workflows/` runs `script/cibuild` on
       push — reference
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/.gitea/workflows/check.yml`

prompts/NEW_REPO_CHECKLIST.md

@@ -1,6 +1,6 @@
 ---
 title: New Repo Checklist
-last_modified: 2026-10-03
+last_modified: 2026-10-04
 ---
 
 Use this checklist when creating a new repository from scratch. Follow the steps
@@ -68,19 +68,24 @@ Template files can be fetched from:
       will run them in subdirectories, `services/api/.claude/` needs its own
       anchored entry.
     - If the image embeds a version in a binary: `.dockerignore` lets `.git`
-      into the build context. It keeps out `.git/config`, which `git describe`
-      does not need and which can hold a credential: a password in a remote URL,
-      or the token the CI checkout step stores there. The stage that compiles
-      has `git` (the Debian Go image has it; an alpine one needs
-      `apk add --no-cache git`) and takes the version from the `VERSION` build
-      argument when one is given, otherwise from `git describe --tags --always`.
-      That gives the tag on a tagged commit; on a later commit, the tag, the
-      number of commits since it and the short commit (`v1.2.3-4-gabc1234`); and
-      the short commit when no tag is reachable. `ARG VERSION` has no default,
-      and the build fails if the context carries `.git` and the version still
-      comes out empty, `dev` or `unknown`. A plain `docker build .` with no
-      build arguments must succeed; a Dockerfile that refuses an empty build
-      argument drops that refusal and keeps the argument.
+      into the build context. It keeps out `.git/config` and each submodule's
+      `config` under `.git/modules/` at any depth (`.git/modules/**/config`),
+      which `git describe` does not need and which can hold a credential: a
+      password in a remote URL, or the token the CI checkout step stores there.
+      The stage that compiles has `git` (the Debian Go image has it; an alpine
+      one needs `apk add --no-cache git`) and takes the version from the
+      `VERSION` build argument when one is given, otherwise from
+      `git describe --tags --always`. That gives the tag on a tagged commit; on
+      a later commit, the tag, the number of commits since it and the short
+      commit (`v1.2.3-4-gabc1234`); and the short commit when no tag is
+      reachable. The stage that compiles also marks its working directory safe
+      for git (`git config --system --add safe.directory /src`): a context sent
+      as a tar stream keeps the sender's file owners, and git refuses a checkout
+      owned by another user, so the version would come out empty. `ARG VERSION`
+      has no default, and the build fails if the context carries `.git` and the
+      version still comes out empty, `dev` or `unknown`. A plain
+      `docker build .` with no build arguments must succeed; a Dockerfile that
+      refuses an empty build argument drops that refusal and keeps the argument.
     - The Dockerfile carries a `lint` phase and a `test` phase, each invoking
       its tool directly rather than through `make` or `script/`, and the final
       stage carries a `COPY --from=` of a harmless file from each so the image

prompts/REPO_POLICIES.md

@@ -1,6 +1,6 @@
 ---
 title: Repository Policies
-last_modified: 2026-10-03
+last_modified: 2026-10-04
 ---
 
 This document covers repository structure, tooling, and workflow standards. Code
@@ -160,7 +160,7 @@ style conventions are in separate documents:
 - **The gate phases are separate stages, and the build stage depends on both.**
   The lint phase is based on the `golangci/golangci-lint` image (pinned by
   hash), so lint failures surface in seconds rather than after a full compile,
-  and the test phase is based on the Go image. The canonical Go repo
+  and the test phase is based on the Debian Go image. The canonical Go repo
   `Dockerfile`:
 
     ```dockerfile
@@ -173,8 +173,9 @@ style conventions are in separate documents:
     COPY . .
     RUN golangci-lint run --config .golangci.yml ./...
 
-    # Test phase
-    # golang:1.x-alpine, YYYY-MM-DD
+    # Test phase. -race needs cgo and so a C compiler, which the Debian Go
+    # image ships and the alpine one does not.
+    # golang:1.x, YYYY-MM-DD
     FROM golang@sha256:... AS test
     WORKDIR /src
     COPY go.mod go.sum ./
@@ -192,6 +193,8 @@ style conventions are in separate documents:
     COPY --from=lint /src/go.sum /dev/null
     COPY --from=test /src/go.sum /dev/null
     RUN apk add --no-cache git
+    # A tar-stream context keeps the sender's file owners, which git refuses.
+    RUN git config --system --add safe.directory /src
     WORKDIR /src
     COPY go.mod go.sum ./
     RUN go mod download
@@ -236,19 +239,23 @@ style conventions are in separate documents:
     - If the project requires CGO or system libraries for linting (e.g.
       `vips-dev`), install them in the lint phase with `apk add`.
     - `.dockerignore` lets `.git` into the build context. It keeps out
-      `.git/config`, which `git describe` does not need and which can hold a
-      credential: a password in a remote URL, or the token the CI checkout step
-      stores there. The stage that compiles has `git` (the Debian Go image has
-      it; an alpine one needs `apk add --no-cache git`) and takes the version
-      from the `VERSION` build argument when one is given, otherwise from
-      `git describe --tags --always`. That gives the tag on a tagged commit; on
-      a later commit, the tag, the number of commits since it and the short
-      commit (`v1.2.3-4-gabc1234`); and the short commit when no tag is
-      reachable. `ARG VERSION` has no default, and the build fails if the
-      context carries `.git` and the version still comes out empty, `dev` or
-      `unknown`. A plain `docker build .` with no build arguments must succeed;
-      a Dockerfile that refuses an empty build argument drops that refusal and
-      keeps the argument.
+      `.git/config` and each submodule's `config` under `.git/modules/` at any
+      depth (`.git/modules/**/config`), which `git describe` does not need and
+      which can hold a credential: a password in a remote URL, or the token the
+      CI checkout step stores there. The stage that compiles has `git` (the
+      Debian Go image has it; an alpine one needs `apk add --no-cache git`) and
+      takes the version from the `VERSION` build argument when one is given,
+      otherwise from `git describe --tags --always`. That gives the tag on a
+      tagged commit; on a later commit, the tag, the number of commits since it
+      and the short commit (`v1.2.3-4-gabc1234`); and the short commit when no
+      tag is reachable. The stage that compiles also marks its working directory
+      safe for git (`git config --system --add safe.directory /src`): a context
+      sent as a tar stream keeps the sender's file owners, and git refuses a
+      checkout owned by another user, so the version would come out empty.
+      `ARG VERSION` has no default, and the build fails if the context carries
+      `.git` and the version still comes out empty, `dev` or `unknown`. A plain
+      `docker build .` with no build arguments must succeed; a Dockerfile that
+      refuses an empty build argument drops that refusal and keeps the argument.
 
 - Every repo should have a Gitea Actions workflow (`.gitea/workflows/`) that
   runs `script/cibuild` on push, and checks out the repo as its only other step.