Rewrite REPO_POLICIES.md sentence by sentence (closes #136)

Every sentence of prompts/REPO_POLICIES.md is rewritten against the
sentence rules: one idea per sentence, about 30 words at most, lists as
bulleted lists, subject and verb early, the main rule before any
exception. No rule's meaning changed: nothing is added, removed,
loosened or tightened, every reason stays, and code blocks, digests,
URLs, file names, commands and quoted strings are unchanged. Both repo
checklists carry the same rewrite of the sentences they quote word for
word.

Model: fable-5-1

.golangci.yml

@@ -3,6 +3,9 @@ version: "2"
 # Config schema uses the golangci-lint v2 layout (settings live under
 # linters.settings, not top-level linters-settings) so that the
 # thresholds below are actually applied by golangci-lint >= v2.
+#
+# This file has no formatters section, so golangci-lint run does not run
+# gofmt. A repository's script/fmt-check runs it, on the host.
 
 run:
   timeout: 5m
@@ -16,17 +19,15 @@ linters:
     - gomodguard_v2
   disable:
     # Genuinely incompatible with project patterns
-    - exhaustruct      # Requires all struct fields
+    - exhaustruct_v5   # Requires all struct fields
-    - exhaustruct_v5   # Requires all struct fields (successor to exhaustruct)
     - godot            # Requires comments to end with periods
     - wrapcheck        # Too verbose for internal packages
     - varnamelen       # Short names like db, id are idiomatic Go
     # Deprecated: the warning is attached to the old name, so it is
     # silenced by disabling that name, not by enabling the successor.
+    - exhaustruct      # Deprecated, replaced by exhaustruct_v5
     - wsl              # Deprecated, replaced by wsl_v5
     - gomodguard       # Deprecated, replaced by gomodguard_v2
-    # Misses findings at random in v2.14.0; back once a pinned release fixes it
-    - canonicalheader
   settings:
     lll:
       line-length: 88
@@ -42,7 +43,10 @@ linters:
       # test-support package exists to hand a test privileges the program
       # itself must never have, so a file that is not a test must not import
       # one. Test files, and the files inside a package whose directory name
-      # ends in `test`, are where that code belongs, and are exempt.
+      # ends in `test`, are where that code belongs, and are exempt. A package
+      # in a subdirectory of that directory is not exempt. `${base-path}` is
+      # the directory holding this file, so the name of the directory a
+      # repository is cloned into does not count.
       #
       # The deny list below is the one part of this file a repository is
       # expected to extend, and the only part it may. depguard matches an
@@ -57,24 +61,25 @@ linters:
           files:
             - "$all"
             - "!$test"
-            - "!**/*test/**"
+            - "!${base-path}**/*test/*"
           deny:
             - pkg: net/http/httptest
               desc: >-
                 Test-support code belongs in test files and in packages whose
                 directory name ends in test, not in the shipped binary.
-    # Only decisions already recorded in the Go package defaults are
+    # Each entry names a module not to use and what to use instead. Every
-    # listed here. Every entry matches the module path exactly.
+    # entry matches the module path exactly.
     gomodguard_v2:
       blocked:
         - module: github.com/rs/zerolog
           recommendations:
             - log/slog
           reason: "Structured logging is stdlib log/slog."
-        # One entry per pre-fork module path, because the later releases
+        # These entries cover only the github.com/go-redis/redis module paths,
-        # are separate paths. A prefix match would be shorter but would
+        # one entry per path, because the later releases are separate paths.
-        # also reach github.com/go-redis/redismock, the test double for
+        # A prefix match would be shorter but would also reach
-        # the successor these entries recommend.
+        # github.com/go-redis/redismock/v9, the test double for the successor
+        # these entries recommend.
         - module: github.com/go-redis/redis
           recommendations:
             - github.com/redis/go-redis/v9
@@ -87,6 +92,10 @@ linters:
           recommendations:
             - github.com/redis/go-redis/v9
           reason: "Pre-fork module; use the maintained go-redis v9."
+        - module: github.com/go-redis/redis/v9
+          recommendations:
+            - github.com/redis/go-redis/v9
+          reason: "Pre-fork module; use the maintained go-redis v9."
         - module: github.com/sergi/go-diff
           recommendations:
             - github.com/aymanbagabas/go-udiff
@@ -110,3 +119,4 @@ linters:
 issues:
   max-issues-per-linter: 0
   max-same-issues: 0
+  uniq-by-line: false

TODO.md

@@ -21,6 +21,53 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-11-04: Rewrote `prompts/REPO_POLICIES.md` sentence by sentence
+  (https://git.eeqj.de/sneak/prompts/issues/136), on sneak's yes at
+  https://git.eeqj.de/sneak/prompts/issues/136#issuecomment-165193. Every rule
+  keeps its meaning and its place, and `must` and `should` stay as they were.
+  Long sentences are split, comma-chained lists are now bulleted lists, and
+  every reason stays. Code blocks, digests, URLs, file names, commands and
+  quoted strings are unchanged.
+- 2026-11-03: The canonical golangci-lint is now v2.15.0, still built with
+  go1.27.0, so the `go` directive rule is unchanged (issue 142). Repositories
+  pick this up on their next re-vendor. Each item in the canonical
+  `.golangci.yml` was tried on a scratch module. These changed:
+    - `canonicalheader` is enabled again, because v2.15.0 fixes the random
+      misses behind issue 105.
+    - The `depguard` exemption covers only the files directly inside a directory
+      whose name ends in `test`. It used to reach every directory below that one
+      too. The name of the directory a repository is cloned into no longer
+      counts.
+    - `gomodguard_v2` also blocks `github.com/go-redis/redis/v9`, whose
+      pre-releases can still be imported under that path.
+    - `uniq-by-line` is now `false`, so a line that trips two linters reports
+      both findings.
+    - Three comments are corrected:
+        - `exhaustruct` is listed as deprecated.
+        - The test double is named `github.com/go-redis/redismock/v9`.
+        - The claim that every blocked module is in the Go package defaults is
+          gone.
+    - A comment says the file has no `formatters` section, so
+      `golangci-lint run` does not run `gofmt`.
+- 2026-11-03: A package from the distribution's own package index now needs no
+  version and no hash, and pulling that index is allowed
+  (https://git.eeqj.de/sneak/prompts/issues/72), on sneak's answer at
+  https://git.eeqj.de/sneak/prompts/issues/72#issuecomment-165196. The
+  distribution is the pinned base image's in a `Dockerfile` and the host's on a
+  host. It is trusted, and everything else stays pinned by hash. A package
+  source that a `Dockerfile` adds itself does not get the exception. The pinning
+  rule of `REPO_POLICIES.md` and both checklists say so, and the canonical Go
+  `Dockerfile`'s `apk add` line has a comment saying why it is allowed.
+- 2026-11-03: A first test run that timed out now gets no verbose rerun
+  (https://git.eeqj.de/sneak/prompts/issues/61), on sneak's approval at
+  https://git.eeqj.de/sneak/prompts/issues/61#issuecomment-165195. The Go recipe
+  in `REPO_POLICIES.md` looks in the first run's output for
+  `panic: test timed out` or `*** Test killed`, and exits 1 when either is
+  there. The Python `make test` example takes the same `timeout 90 sh -c`
+  wrapper as its `Dockerfile` example. The 60 and 90 second rule and the
+  5-minute rule now say a hung package uses the backstop once. The Go item in
+  both repo checklists now asks for this, so a repository with the old recipe
+  fails it.
 - 2026-10-27: Added `prompts/API_POLICIES.md`
   (https://git.eeqj.de/sneak/prompts/issues/137). It holds sneak's rule from
   https://git.eeqj.de/sneak/routewatch/issues/199 that a value in an API

prompts/EXISTING_REPO_CHECKLIST.md

@@ -1,6 +1,6 @@
 ---
 title: Existing Repo Checklist
-last_modified: 2026-10-26
+last_modified: 2026-11-04
 ---
 
 Use this checklist when beginning work in a repo that may not yet conform to our
@@ -56,34 +56,39 @@ with your task.
     - the step that runs `script/bootstrap` to install a Python `test` phase's
       packages from `Pipfile.lock`
 - [ ] A stage with none of these steps declares `ARG CACHEBUST` right after
-      `FROM`. A step that installs anything else as well, such as a
+      `FROM`. A step that also installs anything else comes after
-      `script/bootstrap` that also installs node packages, comes after it too.
+      `ARG CACHEBUST` too. A `script/bootstrap` that also installs node packages
-      The `script/` builds pass a new `CACHEBUST` value on every build, which
+      is one. The `script/` builds pass a new `CACHEBUST` value on every build,
-      reruns every `RUN` step after that line and leaves the layers above it and
+      which reruns every `RUN` step after that line and leaves the layers above
-      the cache mounts in place; `--no-cache` would build those layers again and
+      it and the cache mounts in place; `--no-cache` would build those layers
-      empty the mounts. A stage without the `ARG` line is served from cache on
+      again and empty the mounts. A stage without the `ARG` line is served from
-      an unchanged tree, so the scripts and the `ARG` lines are re-vendored in
+      cache on an unchanged tree, so the scripts and the `ARG` lines are
-      one commit.
+      re-vendored in one commit.
 - [ ] Go: each Go stage downloads the modules (`COPY go.mod go.sum ./`,
       `RUN go mod download`) above `ARG CACHEBUST`; the steps that compile
       (`golangci-lint run`, `go test`, `go build`) mount Go's build cache
       (`--mount=type=cache,target=/root/.cache/go-build`), `golangci-lint run`
       also mounts golangci-lint's
       (`--mount=type=cache,target=/root/.cache/golangci-lint`), and no step
-      mounts anything else; both `go test` runs carry `-count=1`, as in the
+      mounts anything else; both `go test` runs carry `-count=1`; a first run
-      canonical Go `Dockerfile` in `REPO_POLICIES.md`
+      that timed out gets no rerun, as in the canonical Go `Dockerfile` in
+      `REPO_POLICIES.md`
 - [ ] Python: a `test` phase that installs its packages from `Pipfile.lock` does
       it above `ARG CACHEBUST`, with `COPY script/ script/`,
       `COPY Pipfile Pipfile.lock ./` and `RUN script/bootstrap`. When
-      `script/bootstrap` runs in that step, it installs nothing beyond system
+      `script/bootstrap` runs in that step, it installs nothing beyond these:
-      packages, pipenv and its dependencies, and the packages from
+    - system packages
-      `Pipfile.lock`. It installs pipenv and its dependencies by hash, with
+    - pipenv and its dependencies
-      `pip install --require-hashes`. It installs the packages from
+    - the packages from `Pipfile.lock`
-      `Pipfile.lock` with `pipenv install --deploy`, plus `--dev` when the tests
+
-      need the development packages. It installs no Python there, because the
+    It installs pipenv and its dependencies by hash, with
-      tests use the base image's. The tests run after `ARG CACHEBUST`, and every
+    `pip install --require-hashes`. It installs the packages from `Pipfile.lock`
-      other stage installs its Python packages after it, as in the Python `test`
+    with `pipenv install --deploy`, plus `--dev` when the tests need the
-      phase example in `REPO_POLICIES.md`
+    development packages. It installs no Python there, because the tests use the
+    base image's. The tests run after `ARG CACHEBUST`, and every other stage
+    installs its Python packages after it, as in the Python `test` phase example
+    in `REPO_POLICIES.md`
+
 - [ ] The gate phases invoke their tools directly, never through `make lint` or
       `script/test` — those are themselves a `docker build` and would recurse
       inside a build step
@@ -104,37 +109,43 @@ with your task.
       `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 every git `config` at any depth
-      (`**/.git/config`, `**/.git/modules/**/config`): the repository's own,
+      (`**/.git/config`, `**/.git/modules/**/config`):
-      each submodule's under `.git/modules/`, and that of a submodule keeping
+    - the repository's own
-      its own `.git` directory. `git describe` does not need them, and each can
+    - each submodule's under `.git/modules/`
-      hold a credential: a password in a remote URL, or the token the CI
+    - that of a submodule keeping its own `.git` directory
-      checkout step stores there. A submodule whose name has a `config` segment
+
-      (`config`, `deploy/config`, `config/lib`) loses its whole git directory to
+    `git describe` does not need them, and each can hold a credential: a
-      `**/.git/modules/**/config`, and Go's version stamping then fails the
+    password in a remote URL, or the token the CI checkout step stores there.
-      build: give it a name without that segment (`git submodule add --name`).
+    Some submodule names have a `config` segment, as in `config`,
-      The stage that compiles has `git` (the Debian Go image has it; an alpine
+    `deploy/config` or `config/lib`. Such a submodule loses its whole git
-      one needs `apk add --no-cache git`) and takes the version from the
+    directory to `**/.git/modules/**/config`, and Go's version stamping then
-      `VERSION` build argument when one is given, otherwise from
+    fails the build. Give it a name without that segment
-      `git describe --tags --always`. That gives the tag on a tagged commit; on
+    (`git submodule add --name`). The stage that compiles has `git`: the Debian
-      a later commit, the tag, the number of commits since it and the short
+    Go image has it, and an alpine one needs `apk add --no-cache git`. That
-      commit (`v1.2.3-4-gabc1234`); and the short commit when no tag is
+    stage takes the version from the `VERSION` build argument when one is given,
-      reachable. The stage that compiles also marks its working directory safe
+    otherwise from `git describe --tags --always`. That gives:
-      for git (`git config --system --add safe.directory /src`): a context sent
+    - the tag, on a tagged commit
-      as a tar stream keeps the sender's file owners, and git refuses a checkout
+    - the tag, the number of commits since it and the short commit
-      owned by another user, so the version would come out empty. `ARG VERSION`
+      (`v1.2.3-4-gabc1234`), on a later commit
-      has no default, and the build fails if the context carries `.git` and the
+    - the short commit, when no tag is reachable
-      version still comes out empty, `dev` or `unknown`. A plain
+
-      `docker build .` with no build arguments must succeed; a Dockerfile that
+    The stage that compiles also marks its working directory safe for git
-      refuses an empty build argument drops that refusal and keeps the argument.
+    (`git config --system --add safe.directory /src`). A context sent as a tar
-      A checkout whose `.git` is a file (a linked worktree, or a repository
+    stream keeps the sender's file owners, and git refuses a checkout owned by
-      checked out as a submodule) is the exception: that file points to a git
+    another user, so the version would come out empty. `ARG VERSION` has no
-      directory outside the build context, so the build cannot read the version
+    default. The build fails if the context carries `.git` and the version still
-      and a plain `docker build .` fails; pass the version with
+    comes out empty, `dev` or `unknown`. A plain `docker build .` with no build
-      `--build-arg VERSION=...`. `script/docker` and `script/cibuild` already
+    arguments must succeed; a Dockerfile that refuses an empty build argument
-      pass the version they compute on the host; it takes precedence. The
+    drops that refusal and keeps the argument. A checkout whose `.git` is a file
-      canonical `.gitea/workflows/check.yml` sets `fetch-depth: 0` on its
+    is the exception: a linked worktree, or a repository checked out as a
-      checkout step, which otherwise clones shallow and fetches no tags, so a CI
+    submodule. That file points to a git directory outside the build context, so
-      build finds the tag too.
+    the build cannot read the version and a plain `docker build .` fails. Pass
+    the version with `--build-arg VERSION=...`. `script/docker` and
+    `script/cibuild` already pass the version they compute on the host; it takes
+    precedence. The canonical `.gitea/workflows/check.yml` sets `fetch-depth: 0`
+    on its checkout step, which otherwise clones shallow and fetches no tags, so
+    a CI build finds the tag too.
+
 - [ ] Gitea Actions workflow in `.gitea/workflows/` runs `script/cibuild` on
       push, checks out with `persist-credentials: false` and with
       `fetch-depth: 0` (which fetches the tags `git describe` needs), carries
@@ -215,7 +226,12 @@ with your task.
 - [ ] Pre-commit hook is installed (`make hooks`)
 - [ ] No secrets in the repo (`.env`, keys, credentials)
 - [ ] No mutable references in Dockerfiles or scripts (tags, `@latest`) — all
-      pinned by cryptographic hash with version/date comment
+      pinned by cryptographic hash with version/date comment. The one exception
+      is a package from the distribution's own package index, which needs no
+      version and no hash. Pulling that index is also allowed. In a
+      `Dockerfile`, the distribution is the pinned base image's. On a host, it
+      is the host's. A package source that a `Dockerfile` adds itself does not
+      get this exception
 - [ ] Using `yarn`, not `npm` (JS projects)
 
 # Directory Structure

prompts/NEW_REPO_CHECKLIST.md

@@ -1,6 +1,6 @@
 ---
 title: New Repo Checklist
-last_modified: 2026-10-26
+last_modified: 2026-11-04
 ---
 
 Use this checklist when creating a new repository from scratch. Follow the steps
@@ -75,34 +75,42 @@ Template files can be fetched from:
       anchored entry.
     - If the image embeds a version in a binary: `.dockerignore` lets `.git`
       into the build context. It keeps out every git `config` at any depth
-      (`**/.git/config`, `**/.git/modules/**/config`): the repository's own,
+      (`**/.git/config`, `**/.git/modules/**/config`):
-      each submodule's under `.git/modules/`, and that of a submodule keeping
+        - the repository's own
-      its own `.git` directory. `git describe` does not need them, and each can
+        - each submodule's under `.git/modules/`
-      hold a credential: a password in a remote URL, or the token the CI
+        - that of a submodule keeping its own `.git` directory
-      checkout step stores there. A submodule whose name has a `config` segment
+
-      (`config`, `deploy/config`, `config/lib`) loses its whole git directory to
+        `git describe` does not need them, and each can hold a credential: a
-      `**/.git/modules/**/config`, and Go's version stamping then fails the
+        password in a remote URL, or the token the CI checkout step stores
-      build: give it a name without that segment (`git submodule add --name`).
+        there. Some submodule names have a `config` segment, as in `config`,
-      The stage that compiles has `git` (the Debian Go image has it; an alpine
+        `deploy/config` or `config/lib`. Such a submodule loses its whole git
-      one needs `apk add --no-cache git`) and takes the version from the
+        directory to `**/.git/modules/**/config`, and Go's version stamping then
-      `VERSION` build argument when one is given, otherwise from
+        fails the build. Give it a name without that segment
-      `git describe --tags --always`. That gives the tag on a tagged commit; on
+        (`git submodule add --name`). The stage that compiles has `git`: the
-      a later commit, the tag, the number of commits since it and the short
+        Debian Go image has it, and an alpine one needs
-      commit (`v1.2.3-4-gabc1234`); and the short commit when no tag is
+        `apk add --no-cache git`. That stage takes the version from the
-      reachable. The stage that compiles also marks its working directory safe
+        `VERSION` build argument when one is given, otherwise from
-      for git (`git config --system --add safe.directory /src`): a context sent
+        `git describe --tags --always`. That gives:
-      as a tar stream keeps the sender's file owners, and git refuses a checkout
+        - the tag, on a tagged commit
-      owned by another user, so the version would come out empty. `ARG VERSION`
+        - the tag, the number of commits since it and the short commit
-      has no default, and the build fails if the context carries `.git` and the
+          (`v1.2.3-4-gabc1234`), on a later commit
-      version still comes out empty, `dev` or `unknown`. A plain
+        - the short commit, when no tag is reachable
-      `docker build .` with no build arguments must succeed; a Dockerfile that
+
-      refuses an empty build argument drops that refusal and keeps the argument.
+        The stage that compiles also marks its working directory safe for git
-      A checkout whose `.git` is a file (a linked worktree, or a repository
+        (`git config --system --add safe.directory /src`). A context sent as a
-      checked out as a submodule) is the exception: that file points to a git
+        tar stream keeps the sender's file owners, and git refuses a checkout
-      directory outside the build context, so the build cannot read the version
+        owned by another user, so the version would come out empty.
-      and a plain `docker build .` fails; pass the version with
+        `ARG VERSION` has no default. The build fails if the context carries
-      `--build-arg VERSION=...`, as `script/docker` and `script/cibuild` already
+        `.git` and the version still comes out empty, `dev` or `unknown`. A
-      do.
+        plain `docker build .` with no build arguments must succeed; a
+        Dockerfile that refuses an empty build argument drops that refusal and
+        keeps the argument. A checkout whose `.git` is a file is the exception:
+        a linked worktree, or a repository checked out as a submodule. That file
+        points to a git directory outside the build context, so the build cannot
+        read the version and a plain `docker build .` fails. Pass the version
+        with `--build-arg VERSION=...`, as `script/docker` and `script/cibuild`
+        already do.
+
     - 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
@@ -115,37 +123,43 @@ Template files can be fetched from:
         - the step that runs `script/bootstrap` to install a Python `test`
           phase's packages from `Pipfile.lock`
     - A stage with none of these steps declares `ARG CACHEBUST` right after
-      `FROM`. A step that installs anything else as well, such as a
+      `FROM`. A step that also installs anything else comes after
-      `script/bootstrap` that also installs node packages, comes after it too.
+      `ARG CACHEBUST` too. A `script/bootstrap` that also installs node packages
-      The `script/` builds pass a new `CACHEBUST` value on every build, which
+      is one. The `script/` builds pass a new `CACHEBUST` value on every build,
-      reruns every `RUN` step after that line and leaves the layers above it and
+      which reruns every `RUN` step after that line and leaves the layers above
-      the cache mounts in place; `--no-cache` would build those layers again and
+      it and the cache mounts in place; `--no-cache` would build those layers
-      empty the mounts. A stage without the `ARG` line is served from cache on
+      again and empty the mounts. A stage without the `ARG` line is served from
-      an unchanged tree, so the scripts and every stage's `ARG CACHEBUST` line
+      cache on an unchanged tree, so the scripts and every stage's
-      are added in the same commit.
+      `ARG CACHEBUST` line are added in the same commit.
     - Go: each Go stage downloads the modules (`COPY go.mod go.sum ./`,
       `RUN go mod download`) above `ARG CACHEBUST`; the steps that compile
       (`golangci-lint run`, `go test`, `go build`) mount Go's build cache
       (`--mount=type=cache,target=/root/.cache/go-build`), `golangci-lint run`
       also mounts golangci-lint's
       (`--mount=type=cache,target=/root/.cache/golangci-lint`), and no step
-      mounts anything else; both `go test` runs carry `-count=1`, as in the
+      mounts anything else; both `go test` runs carry `-count=1`; a first run
-      canonical Go `Dockerfile` in `REPO_POLICIES.md`
+      that timed out gets no rerun, as in the canonical Go `Dockerfile` in
+      `REPO_POLICIES.md`
     - Python: a `test` phase that installs its packages from `Pipfile.lock` does
       it above `ARG CACHEBUST`, with `COPY script/ script/`,
       `COPY Pipfile Pipfile.lock ./` and `RUN script/bootstrap`. When
-      `script/bootstrap` runs in that step, it installs nothing beyond system
+      `script/bootstrap` runs in that step, it installs nothing beyond these:
-      packages, pipenv and its dependencies, and the packages from
+        - system packages
-      `Pipfile.lock`. It installs pipenv and its dependencies by hash, with
+        - pipenv and its dependencies
-      `pip install --require-hashes`. It installs the packages from
+        - the packages from `Pipfile.lock`
-      `Pipfile.lock` with `pipenv install --deploy`, plus `--dev` when the tests
+
-      need the development packages. It installs no Python there, because the
+        It installs pipenv and its dependencies by hash, with
-      tests use the base image's. The tests run after `ARG CACHEBUST`, and every
+        `pip install --require-hashes`. It installs the packages from
-      other stage installs its Python packages after it, as in the Python `test`
+        `Pipfile.lock` with `pipenv install --deploy`, plus `--dev` when the
-      phase example in `REPO_POLICIES.md`
+        tests need the development packages. It installs no Python there,
+        because the tests use the base image's. The tests run after
+        `ARG CACHEBUST`, and every other stage installs its Python packages
+        after it, as in the Python `test` phase example in `REPO_POLICIES.md`
+
     - Server: the final stage builds and runs the application
     - Non-server: the final stage brings up the dev environment
     - Image pinned by sha256 hash with version/date comment
+
 - [ ] Gitea Actions workflow at `.gitea/workflows/check.yml` that runs
       `script/cibuild` on push, checks out with `persist-credentials: false` and
       with `fetch-depth: 0` (which fetches the tags `git describe` needs),
@@ -242,7 +256,11 @@ are thin shims calling them. Model scripts:
       final stage is missing its `COPY --from=` edge to the gate phases.
 - [ ] No secrets in repo, and none in the build context: enumerate a probe image
       rather than reading `.dockerignore`
-- [ ] No mutable image/package references
+- [ ] No mutable image/package references. The one exception is a package from
+      the distribution's own package index, which needs no version and no hash.
+      Pulling that index is also allowed. In a `Dockerfile`, the distribution is
+      the pinned base image's. On a host, it is the host's. A package source
+      that a `Dockerfile` adds itself does not get this exception
 - [ ] No unnecessary files in repo root
 - [ ] All dates written as YYYY-MM-DD