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Keep Go's build cache in check builds: re-vendor sneak/prompts e3f79c4 (closes #129)
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The vendored files are copies from sneak/prompts e3f79c4, with this
repository's own entries kept. The script/ builds pass a new CACHEBUST
value instead of --no-cache, which emptied Go's build cache mount, so
every make test compiled the standard library and every dependency with
-race. Every Dockerfile stage declares ARG CACHEBUST first, so every RUN
step still reruns on an unchanged tree. The steps that compile mount
Go's build cache, and both go test runs keep -count=1. The lint and test
builds write no image. script/bootstrap, script/fmt and script/fmt-check
are the canonical files plus this repository's Go steps.

Model: opus-5-5
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sneak
2026-10-15 17:26:16 +00:00
parent 8851171877
commit c9bafb962d
18 changed files with 336 additions and 158 deletions
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REPO_POLICIES.md
+156 -79
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@@ -1,6 +1,6 @@
---
title: Repository Policies
last_modified: 2026-10-04
last_modified: 2026-10-15
---
This document covers repository structure, tooling, and workflow standards. Code
@@ -54,34 +54,39 @@ style conventions are in separate documents:
`cibuild`. `script/bootstrap` installs all dependencies idempotently and
assumes nothing is present: base tools come from nix, apt, brew, or apk
(detected in that order; apt runs noninteractive). For node it uses the
installed node if present; otherwise it installs a PINNED node version via
nvm, first installing nvm itself if missing — from a hash-verified GitHub
release archive (never `curl | sh`), with bash installed as an explicit
prerequisite since nvm requires bash. yarn is then pinned via
`corepack prepare yarn@<version> --activate`. Never install "latest" or "lts";
always exact versions. `script/cibuild` runs the CI build: it changes to the
repo root, runs `script/bootstrap`, runs `script/check`, and builds the image
with the version; the Gitea workflow calls it. **`script/cibuild` runs
installed node only when its major version is the pinned one; otherwise (node
missing, or another major, such as the node 24 the CI runner image ships) it
installs the PINNED node version via nvm and installs yarn and the packages
under it. nvm itself is installed first if missing, from a hash-verified
GitHub release archive (never `curl | sh`), with bash installed as an explicit
prerequisite since nvm requires bash. Only the major version is compared
because the `Dockerfile` stages start from a node image whose exact version is
not the pin, and nvm cannot install a prebuilt node on alpine. yarn is pinned
via `corepack prepare yarn@<version> --activate`. Never install "latest" or
"lts"; always exact versions. `script/cibuild` runs the CI build: it changes
to the repo root, runs `script/bootstrap`, runs `script/check`, and builds the
image with the version; the Gitea workflow calls it. **`script/cibuild` runs
`script/bootstrap` first**, because the workflow checks out the repo and runs
nothing else, while `script/fmt-check` runs the formatter on the host: on a
pristine checkout with nothing installed the run dies there, after the
containerised gates have passed. **The bootstrap alone is not enough**:
`script/bootstrap` installs node and yarn under nvm and leaves neither on the
`PATH` of the shell that called it, so a bare `yarn` still exits 127. The host
entrypoints that need yarn — `script/fmt` and `script/fmt-check` — therefore
source nvm for the pinned node version before invoking it, exactly as
`script/bootstrap`'s own install step does. A runner carrying nothing but
docker and git then gets through `script/check`. Four further scripts are our
own extensions to the standard: `script/check` runs `script/test`,
`script/lint` and `script/fmt-check`; `script/precommit` is what the git
pre-commit hook runs, and it calls `script/check`; `script/install-precommit`
installs the git pre-commit hook (the `make hooks` target shims to it); and
`script/projectname` (literally that filename) simply outputs the project's
name. Scripts that need the name call `script/projectname` — e.g.
`script/docker` assembles its image tag from it — so those scripts stay
byte-identical across all repos. Repo-type-specific pre-commit extras (e.g.
`go mod tidy` verification in Go repos) belong in `script/precommit`, not in
the hook itself. Model scripts are at
containerised gates have passed. **The bootstrap alone is not enough**: when
`script/bootstrap` installs node and yarn under nvm it leaves neither on the
`PATH` of the shell that called it, so a bare `yarn` either exits 127 or runs
under another node. The host entrypoints that need yarn — `script/fmt` and
`script/fmt-check` — therefore use the same test as `script/bootstrap`: when
the node on `PATH` has the pinned major version they run the `yarn` on `PATH`,
and otherwise they load nvm through `$HOME/.nvm/nvm.sh` and run yarn under the
pinned node. A runner carrying nothing but docker and git then gets through
`script/check`. Four further scripts are our own extensions to the standard:
`script/check` runs `script/test`, `script/lint` and `script/fmt-check`;
`script/precommit` is what the git pre-commit hook runs, and it calls
`script/check`; `script/install-precommit` installs the git pre-commit hook
(the `make hooks` target shims to it); and `script/projectname` (literally
that filename) simply outputs the project's name. Scripts that need the name
call `script/projectname` — e.g. `script/docker` assembles its image tag from
it — so those scripts stay byte-identical across all repos. Repo-type-specific
pre-commit extras (e.g. `go mod tidy` verification in Go repos) belong in
`script/precommit`, not in the hook itself. Model scripts are at
`https://git.eeqj.de/sneak/prompts/raw/branch/main/script/<name>`. The README
must document the provided scripts in an **Entrypoints** section (see the
README requirements below).
@@ -118,8 +123,10 @@ style conventions are in separate documents:
and nothing else:
```sh
docker build --no-cache --target lint -t "$(script/projectname)-lint" .
docker build --no-cache --target test -t "$(script/projectname)-test" .
docker build --build-arg CACHEBUST="$(date +%s)-$$" \
--target lint --output type=cacheonly .
docker build --build-arg CACHEBUST="$(date +%s)-$$" \
--target test --output type=cacheonly .
```
**A stage that is not the last one in the file is built only when the final
@@ -129,10 +136,15 @@ style conventions are in separate documents:
plain `docker build .` builds the last stage alone and exits 0 having linted
and tested nothing.
**Every `docker build` in `script/` is tagged**, here and in
`script/cibuild` and `script/docker`. An untagged build leaves a dangling
image behind on every invocation, on every developer host and every CI
runner; a tagged one replaces the previous image.
**The gate builds write no image.** With `--output type=cacheonly` the phase
runs and a failing step fails the build, but the result is not exported.
Nothing uses those images, and writing one out is slow: a Go test phase's
image holds the toolchain. A build given neither `--output` nor `-t` writes
an untagged image and leaves it dangling, on every developer host and every
CI runner. `script/cibuild` and `script/docker` build the image that ships
and tag it, so each build replaces the previous image; each assigns the tag
on its own line before the build, so `set -e` stops it where
`script/projectname` fails.
Inside a phase the tool is invoked directly — `golangci-lint`, `go test`,
`eslint`, `prettier` — never through `make lint` or `script/test`, which are
@@ -147,22 +159,33 @@ style conventions are in separate documents:
one's findings, and a host-global lock in `$TMPDIR` makes concurrent runs
exit non-zero with `parallel golangci-lint is running` — a status a caller
cannot tell from real findings. Both have produced wrong verdicts in this
org, in both directions. A container has its own cache, its own `TMPDIR` and
a digest-pinned binary, so neither is reachable.
org, in both directions. A container has its own golangci-lint cache, its
own `TMPDIR` and a digest-pinned binary, so neither is reachable.
- **Any build that runs checks is built with `--no-cache`.** Docker invalidates
a `COPY` layer only when the copied content changes, so on an unchanged tree
the check `RUN` is served from cache, nothing executes, and the build still
exits 0. Every `docker build` in `script/` therefore passes `--no-cache`:
`script/lint`, `script/test`, `script/cibuild` and `script/docker` are the
four, and there is no fifth — `script/check` runs the two gate phases and
`script/fmt-check`, and builds no image of its own. A bare `docker build .` is
not evidence that anything ran: a sub-second build reporting success is a
cache hit, not a result. Never invalidate by pruning — `docker builder prune`
and friends destroy a build cache shared with every other build on the host.
When a check is added or changed, prove it works by planting a defect it must
catch and watching the run fail on it, then revert the defect. A green run
alone shows neither that the check ran nor that it covers what it should.
- **Any build that runs checks is given a new `CACHEBUST` value.** Docker
invalidates a `COPY` layer only when the copied content changes, so on an
unchanged tree the check `RUN` is served from cache, nothing executes, and the
build still exits 0. Every `docker build` in `script/` therefore passes
`--build-arg CACHEBUST="$(date +%s)-$$"`, the time and the script's process
id, so no two builds share a value, not even the three in one
`script/cibuild`. `script/lint`, `script/test`, `script/cibuild` and
`script/docker` are the four, and there is no fifth — `script/check` runs the
two gate phases and `script/fmt-check`, and builds no image of its own. Every
stage of the `Dockerfile` declares `ARG CACHEBUST` as its first line after
`FROM`, and a new value reruns every `RUN` step after that line; `COPY` steps
are compared by content and need nothing. A stage without the `ARG` line is
served from cache on an unchanged tree, so a repository re-vendors the scripts
and adds the `ARG` lines in one commit. The scripts do not pass `--no-cache`:
it reruns every step too, but it also empties every cache mount, and Go's
build cache, which the canonical Go `Dockerfile` below mounts so that compiled
packages survive between check builds, would start empty every time. A bare
`docker build .` is not evidence that anything ran: a sub-second build
reporting success is a cache hit, not a result. Never invalidate by pruning —
`docker builder prune` and friends destroy a build cache shared with every
other build on the host. When a check is added or changed, prove it works by
planting a defect it must catch and watching the run fail on it, then revert
the defect. A green run alone shows neither that the check ran nor that it
covers what it should.
- **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
@@ -171,32 +194,42 @@ style conventions are in separate documents:
`Dockerfile`:
```dockerfile
# Every stage declares ARG CACHEBUST first: script/ passes a new value
# on every build, which reruns every RUN step after it. The steps that
# compile mount Go's build cache, which survives from build to build.
# Lint phase
# golangci/golangci-lint:v2.x.x, YYYY-MM-DD
FROM golangci/golangci-lint@sha256:... AS lint
ARG CACHEBUST
WORKDIR /src
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN golangci-lint run --config .golangci.yml ./...
RUN --mount=type=cache,target=/root/.cache/go-build \
golangci-lint run --config .golangci.yml ./...
# Test phase. -race needs cgo and so a C compiler, which the Debian Go
# image ships and the alpine one does not.
# image ships and the alpine one does not. -count=1 because the mounted
# cache also holds test results, which go test would otherwise replay.
# golang:1.x, YYYY-MM-DD
FROM golang@sha256:... AS test
ARG CACHEBUST
WORKDIR /src
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN go test -timeout 90s -race -cover ./... || \
RUN --mount=type=cache,target=/root/.cache/go-build \
go test -count=1 -timeout 90s -race -cover ./... || \
{ echo "--- Rerunning with -v for details ---"; \
go test -timeout 90s -race -v ./...; exit 1; }
go test -count=1 -timeout 90s -race -v ./...; exit 1; }
# Build stage. Nothing is wanted from either phase above; the copies
# are what make BuildKit build them first, so this stage cannot run
# unless lint and test passed.
# golang:1.x-alpine, YYYY-MM-DD
FROM golang@sha256:... AS builder
ARG CACHEBUST
COPY --from=lint /src/go.sum /dev/null
COPY --from=test /src/go.sum /dev/null
RUN apk add --no-cache git
@@ -212,7 +245,8 @@ style conventions are in separate documents:
# .git present, a version that is still empty, dev or unknown fails the
# build: git is missing or could not read the checkout.
ARG VERSION
RUN VERSION="${VERSION:-$(git describe --tags --always)}"; \
RUN --mount=type=cache,target=/root/.cache/go-build \
VERSION="${VERSION:-$(git describe --tags --always)}"; \
if [ -e .git ]; then \
case "$VERSION" in ""|dev|unknown) \
echo "version is '$VERSION' although .git is present" >&2; \
@@ -225,6 +259,7 @@ style conventions are in separate documents:
# Runtime stage, and the last one
FROM alpine@sha256:...
ARG CACHEBUST
COPY --from=builder /app /usr/local/bin/app
ENTRYPOINT ["app"]
```
@@ -239,6 +274,16 @@ style conventions are in separate documents:
- Keep the runtime stage last, and if you add a stage after it, give it the
same two copies. A plain `docker build .` builds the last stage's chain
and nothing else.
- Only Go's build cache is mounted (`/root/.cache/go-build`, where Go keeps
it for root), and only on the steps that compile: `golangci-lint run`,
both `go test` runs and `go build`. It keeps compiled packages between
check builds, and Go reuses one only when all its inputs are unchanged, so
it saves the compile without skipping a check. Nothing else is kept:
golangci-lint's own cache would replay stored findings in place of a lint
run, and Go builds from whatever files a kept module cache holds without
checking them again (only `go mod verify` does), so a file changed there
would go unnoticed. Go's build cache also holds test results, which is why
both `go test` runs carry `-count=1`.
- If the project uses `//go:embed` directives that reference build artifacts
(e.g. a web frontend compiled in a separate stage), the lint phase must
create placeholder files so the embed directives resolve. Example:
@@ -278,20 +323,39 @@ style conventions are in separate documents:
`.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.
A checkout whose `.git` is a file (a linked worktree, or a repository
checked out as a submodule) is the exception: 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.
- 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.
That script bootstraps, runs the gate phases, and then builds the image, so a
successful run means every check passed; a bare `docker build .` does not
runs `script/cibuild` on push, and checks out the repo as its only other step,
with `persist-credentials: false`: `script/cibuild` needs no token, and
without it the checkout leaves the job's token in `.git/config` for every
later step. The checkout step also sets `fetch-depth: 0`, which fetches the
tags `git describe` needs: by default it clones shallow with no tags, and a
tagged repository's CI build would stamp a bare short commit id. The
workflow's `concurrency` block groups runs by workflow and branch
(`${{ github.workflow }}-${{ github.ref }}`) with `cancel-in-progress: true`,
so a new push cancels the older run on the same branch, queued or running, and
no other: runs for replaced commits do not hold up the shared runner.
`script/cibuild` bootstraps, runs the gate phases, and then builds the image,
so a successful run means every check passed; a bare `docker build .` does not
carry the same guarantee, because its gate phases may come from the cache. The
image build is uncached and so runs the gate phases a second time. That is the
price of the rule above, and it is worth paying: the image that ships is built
from a run of its own gates rather than from a cache entry. A separate
workflow limited to `main` by a `branches` list under `on: push` cannot be
checked by review: to try a change to it, add the feature branch to that list
and push, then remove the branch from the list again before merging. Keep any
job in it that publishes behind `if: github.ref_name == 'main'`, so the run
from the feature branch publishes nothing.
image build gets a `CACHEBUST` value of its own and so runs the gate phases a
second time. That is the price of the rule above, and it is worth paying: the
image that ships is built from a run of its own gates rather than from a cache
entry. The `check` job sets `timeout-minutes: 20`, so a hung build frees the
shared runner after 20 minutes. That allows for the three Docker builds
described above (the test phase, the lint phase, then the image), each held to
the 5-minute Docker build limit below, plus the bootstrap. A separate workflow
limited to `main` by a `branches` list under `on: push` cannot be checked by
review: to try a change to it, add the feature branch to that list and push,
then remove the branch from the list again before merging. Keep any job in it
that publishes behind `if: github.ref_name == 'main'`, so the run from the
feature branch publishes nothing.
- Use platform-standard formatters: `black` for Python, `prettier` for
JS/CSS/Markdown/HTML, `go fmt` for Go. Always use default configuration with
@@ -351,12 +415,11 @@ style conventions are in separate documents:
That cache is Go's own, separate from Docker's layer cache. Go stores a
passing result in its cache directory (`GOCACHE`), and when the same tests
run again on unchanged code it prints that result, marked `(cached)`,
without running them. That matters on a developer's machine, where this
target runs and the directory lasts from one run to the next. The `test`
phase of the `Dockerfile` needs no `-count=1`: its base image holds no
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.
without running them. The directory lasts from one run to the next on a
developer's machine, where this target runs, and in the `test` phase of the
`Dockerfile`, which mounts it to keep compiled packages between check
builds, so the phase's `go test` runs carry `-count=1` too. A new
`CACHEBUST` value (above) is what makes that step run on an unchanged tree.
Python example:
@@ -384,9 +447,12 @@ style conventions are in separate documents:
- `.gitignore` should be comprehensive from the start: OS files (`.DS_Store`),
editor files (`.swp`, `*~`), in-repo agent scratch directories (`.claude/`),
language build artifacts, and `node_modules/`. Fetch the standard `.gitignore`
from `https://git.eeqj.de/sneak/prompts/raw/branch/main/.gitignore` when
setting up a new repo. These patterns are written to `.gitignore`'s own
`node_modules/`, and the repo's own build outputs. Fetch the standard
`.gitignore` from
`https://git.eeqj.de/sneak/prompts/raw/branch/main/.gitignore` when setting up
a new repo. A repo's `.gitignore` is the standard file followed by the repo's
own entries, such as its binaries; a re-vendor replaces the standard part and
keeps those entries. These patterns are written to `.gitignore`'s own
semantics, in which an unanchored pattern already matches at every depth; they
are not a `.dockerignore` and must not be transplanted into one unmodified.
@@ -434,13 +500,15 @@ style conventions are in separate documents:
byte-identically across repos:
```sh
# Own line: a failing command substitution inside an argument does not
# trip `set -e`, so the inline form degrades to an empty constant.
# The version and the tag each get their own line: a failing command
# substitution inside an argument does not trip `set -e`, so the inline
# form degrades to an empty constant.
version="$(git describe --tags --always --dirty 2>/dev/null || true)"
[ -n "$version" ] || version="unknown"
docker build --no-cache \
tag="$(script/projectname)"
docker build --build-arg CACHEBUST="$(date +%s)-$$" \
--build-arg VERSION="$version" \
-t "$(script/projectname)" .
-t "$tag" .
```
`--always` makes an untagged repo yield an abbreviated commit hash rather
@@ -452,8 +520,8 @@ style conventions are in separate documents:
there because `ARG` is stage-scoped; passing `VERSION` to a repo whose
Dockerfile declares no such `ARG` is ignored and costs nothing, which is why
the scripts stay byte-identical. One consequence for CI: the standard
checkout action clones shallow and fetches no tags, so a repo that embeds a
tag-derived version must set `fetch-depth: 0` on its checkout step.
checkout action clones shallow and fetches no tags, so the canonical
`.gitea/workflows/check.yml` sets `fetch-depth: 0` on its checkout step.
- **Verify `.dockerignore` by enumerating the image, not by reading the
patterns.** Plant files at the root _and_ at least two directories deep, build
@@ -520,6 +588,11 @@ style conventions are in separate documents:
function defined and never invoked has the same exit status and the same
empty output as one that worked.
Node is the exception to the whole-token comparison: the canonical
`script/bootstrap` compares only its major version, because the node 22
alpine image the `Dockerfile` stages start from is not the exact pin, and
nvm cannot install a prebuilt node on alpine.
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
@@ -636,7 +709,11 @@ style conventions are in separate documents:
Never edit existing migrations after release.
- All repos should have an `.editorconfig` enforcing the project's indentation
settings.
settings: the standard file from
`https://git.eeqj.de/sneak/prompts/raw/branch/main/.editorconfig`, which sets
tabs for `Makefile` and Go files, followed by the repo's own sections, such as
one for another language it uses. A re-vendor replaces the standard part and
keeps those sections.
- Avoid putting files in the repo root unless necessary. Root should contain
only project-level config files (`README.md`, `AGENTS.md`, `Makefile`,