Fold the August fleet findings into the policies, or drop them (closes #62)

Of the cross-repository findings recorded on 2026-08-09, two were rules a repository must follow that `prompts/REPO_POLICIES.md` did not yet state, and each now sits in the paragraph a reader would be in. A new or changed check is proven by planting a defect it must catch and watching the run fail, since a green run alone does not show the check ran. A separate workflow limited to `main` by a `branches` list is first run from the feature branch by adding that branch to the list and removing it before merging, with any publishing job kept behind `if: github.ref_name == 'main'`.

The other findings are dropped, each with its reason on the issue; the `config verify` warning goes by sneak's ruling on #40 that there is no config check step.

Model: opus-5-5

.dockerignore

@@ -18,9 +18,16 @@
 # 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.
+# under .git/modules/, nested again for a submodule's own submodules, or in
-.git/config
+# its own .git directory when it keeps one.
-.git/modules/**/config
+# KNOWN GAP: a submodule whose name has a `config` segment (`config`,
+# `deploy/config`, `config/lib`) loses its whole git directory, because
+# `**/.git/modules/**/config` also matches that segment's directory
+# under .git/modules/. Go's version stamping then fails the build;
+# nothing leaks. Name such a submodule without that segment:
+# `git submodule add --name`.
+**/.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.
@@ -44,7 +51,9 @@
 **/[iI][dD]_[rR][sS][aA]
 **/[iI][dD]_[dD][sS][aA]
 **/[iI][dD]_[eE][cC][dD][sS][aA]
+**/[iI][dD]_[eE][cC][dD][sS][aA]_[sS][kK]
 **/[iI][dD]_[eE][dD]25519
+**/[iI][dD]_[eE][dD]25519_[sS][kK]
 
 # Dependencies: restored inside the image, never copied in.
 **/node_modules

.gitattributes

@@ -0,0 +1,4 @@
+# Every PR adds an entry at the top of TODO.md's Completed Steps; union keeps
+# both sides instead of conflicting. Git never reports a conflict here: read
+# the merged entries after every merge or rebase.
+TODO.md merge=union

.gitignore

@@ -42,4 +42,6 @@ node_modules/
 [iI][dD]_[rR][sS][aA]
 [iI][dD]_[dD][sS][aA]
 [iI][dD]_[eE][cC][dD][sS][aA]
+[iI][dD]_[eE][cC][dD][sS][aA]_[sS][kK]
 [iI][dD]_[eE][dD]25519
+[iI][dD]_[eE][dD]25519_[sS][kK]

TODO.md

@@ -21,6 +21,79 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-10-04: Went through the fleet findings recorded on 2026-08-09 (issue 62)
+  and added the two rules `REPO_POLICIES.md` did not yet state: a new or changed
+  check is proven by planting a defect it must catch; and a change to a separate
+  workflow limited to `main` is first run from the feature branch, added to that
+  workflow's `branches` list and removed again before merging. The other
+  findings were already stated, replaced by `--no-cache`, about git worktrees,
+  or about how agents work together. The warning against
+  `golangci-lint config verify` is dropped because sneak ruled on
+  https://git.eeqj.de/sneak/prompts/issues/40 (2026-08-10) that there is no
+  config check step and the config is assumed valid; a vendored `.golangci.yml`
+  stays byte-identical to the canonical copy. The issue gives each reason.
+- 2026-10-04: `REPO_POLICIES.md` now says which `Dockerfile` stages run
+  `script/bootstrap` (issue 90). The gate phases and the build stage start from
+  their pinned base images and install what those images lack either inline, as
+  the canonical Go `Dockerfile` does for `git`, or by running
+  `script/bootstrap`, as this repo's own `Dockerfile` does for its yarn
+  packages. The development environment stage, the final stage of a non-server
+  repo, runs `script/bootstrap`. The new repo checklist says the same.
+- 2026-10-04: Added a root `.gitattributes` that merges `TODO.md` with git's
+  union merge (issue 98), so two branches that each add an entry at the top of
+  Completed Steps merge without a conflict. Git now never reports a conflict in
+  `TODO.md`: a real conflict elsewhere keeps both versions of the line, and when
+  two new entries share an identical line, one is inserted into the middle of
+  the other, which a rebase can do to an entry already on `next`. Read the
+  merged entries after every merge or rebase. This applies to this repository
+  only; no canonical file changed.
+- 2026-10-04: The canonical `.dockerignore` now also keeps out the git `config`
+  of a submodule that keeps its own `.git` directory, which still reached the
+  image (issue 88): both git patterns now carry the `**/` prefix. A submodule
+  whose name has a `config` segment (`config`, `deploy/config`, `config/lib`)
+  still loses its whole git directory, so Go's version stamping fails the build;
+  the file records this as a `KNOWN GAP:` with the remedy,
+  `git submodule add --name`. Closing it would take a wildcard re-include, which
+  makes BuildKit walk every excluded directory, such as `node_modules`, on every
+  build. `REPO_POLICIES.md` and both checklists say so in the same words.
+- 2026-10-04: The note under the canonical Go `Dockerfile` example in
+  `REPO_POLICIES.md` now installs lint-phase system libraries with `apt-get`
+  under their Debian package names (issue 83). The `golangci/golangci-lint`
+  image is Debian-based and has no `apk`, so the old `apk add` instruction
+  failed as written. Nothing is pinned or unpinned; that is still open on
+  issue 72.
+- 2026-10-04: Fixed the server lifecycle example in
+  `prompts/GO_HTTP_SERVER_CONVENTIONS.md` (issue 86). Only fx handles SIGINT and
+  SIGTERM, and `Run()` in `main` exits with the shutdown's exit code. A listen
+  error asks fx to shut down with exit code 1 through `fx.Shutdowner`; a Sentry
+  start failure is returned from the server's start hook instead of calling
+  `os.Exit` from a goroutine, so the stop hooks of what had started still run.
+  The server's stop hook shuts the HTTP server down within 5 seconds and fails
+  when requests are still running. A new paragraph says who owns signals and the
+  exit code.
+- 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
+  stay trackable.
+- 2026-10-04: `package.json` now has `"license": "MIT"`, matching `LICENSE`, so
+  yarn no longer prints "No license field" when `script/bootstrap` runs it
+  inside the Docker phases (issue 76). That was the only yarn warning there.
+- 2026-10-04: `REPO_POLICIES.md` now states that guidance for coding agents
+  lives in one `AGENTS.md` at the repository root, never under a file or
+  directory named after one agent tool and never in separate memory files (issue
+  31). This retires the rule, still present in older vendored copies, that kept
+  agent memory as committed files under `.claude/memory/`. `AGENTS.md` joins the
+  list of files allowed in the root, and both checklists say so.
+- 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

package.json

@@ -1,4 +1,5 @@
 {
+  "license": "MIT",
   "devDependencies": {
     "prettier": "3.8.1"
   }

prompts/EXISTING_REPO_CHECKLIST.md

@@ -24,6 +24,10 @@ with your task.
 - [ ] `LICENSE` file exists and matches the README
 - [ ] `REPO_POLICIES.md` exists and version date is current — fetch from
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/REPO_POLICIES.md`
+- [ ] Guidance for coding agents, if the repo has any, is one `AGENTS.md` at the
+      root — never a file or directory named after one agent tool, such as
+      `CLAUDE.md` or `.claude/`, and never separate memory files. Move what any
+      such committed file says into `AGENTS.md` and delete it.
 - [ ] `.gitignore` is comprehensive (OS, editor, agent scratch, language
       artifacts, secrets) — fetch from
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/.gitignore` if missing.
@@ -59,10 +63,15 @@ 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` and each submodule's
+      the build context. It keeps out every git `config` at any depth
-      `config` under `.git/modules/` at any depth (`.git/modules/**/config`),
+      (`**/.git/config`, `**/.git/modules/**/config`): the repository's own,
-      which `git describe` does not need and which can hold a credential: a
+      each submodule's under `.git/modules/`, and that of a submodule keeping
-      password in a remote URL, or the token the CI checkout step stores there.
+      its own `.git` directory. `git describe` does not need them, and each can
+      hold a credential: a password in a remote URL, or the token the CI
+      checkout step stores there. A submodule whose name has a `config` segment
+      (`config`, `deploy/config`, `config/lib`) loses its whole git directory to
+      `**/.git/modules/**/config`, and Go's version stamping then fails the
+      build: give it a name without that segment (`git submodule add --name`).
       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

prompts/GO_HTTP_SERVER_CONVENTIONS.md

@@ -106,6 +106,9 @@ project-root/
 package main
 
 import (
+    "os/signal"
+    "syscall"
+
     "yourproject/internal/config"
     "yourproject/internal/database"
     "yourproject/internal/globals"
@@ -126,6 +129,9 @@ func main() {
     globals.Appname = Appname
     globals.Version = Version
 
+    // A write to a closed stdout or stderr must not end the process.
+    signal.Ignore(syscall.SIGPIPE)
+
     fx.New(
         fx.Provide(
             config.New,
@@ -198,7 +204,8 @@ Providers are resolved automatically by fx, but conceptually follow this order:
    Database)
 6. `middleware.New` - Middleware (depends on Logger, Globals, Config)
 7. `handlers.New` - Handlers (depends on Logger, Globals, Database, Healthcheck)
-8. `server.New` - Server (depends on all above)
+8. `server.New` - Server (depends on all above, and on `fx.Shutdowner`, which fx
+   provides itself)
 
 ---
 
@@ -217,16 +224,14 @@ type ServerParams struct {
     Config     *config.Config
     Middleware *middleware.Middleware
     Handlers   *handlers.Handlers
+    Shutdowner fx.Shutdowner
 }
 
 type Server struct {
     startupTime   time.Time
     port          int
-    exitCode      int
     sentryEnabled bool
     log           *slog.Logger
-    ctx           context.Context
-    cancelFunc    context.CancelFunc
     httpServer    *http.Server
     router        *chi.Mux
     params        ServerParams
@@ -248,13 +253,15 @@ func New(lc fx.Lifecycle, params ServerParams) (*Server, error) {
     lc.Append(fx.Hook{
         OnStart: func(ctx context.Context) error {
             s.startupTime = time.Now()
-            go s.Run()
+            if err := s.enableSentry(); err != nil {
-            return nil
+                return err
-        },
+            }
-        OnStop: func(ctx context.Context) error {
+            s.SetupRoutes()
-            // Server shutdown logic
+            s.httpServer = s.newHTTPServer()
+            go s.serveUntilShutdown()
             return nil
         },
+        OnStop: s.cleanShutdown,
     })
     return s, nil
 }
@@ -264,23 +271,25 @@ func New(lc fx.Lifecycle, params ServerParams) (*Server, error) {
 
 ```go
 // internal/server/http.go
-func (s *Server) serveUntilShutdown() {
+func (s *Server) newHTTPServer() *http.Server {
-    listenAddr := fmt.Sprintf(":%d", s.params.Config.Port)
+    return &http.Server{
-    s.httpServer = &http.Server{
+        Addr:           fmt.Sprintf(":%d", s.params.Config.Port),
-        Addr:           listenAddr,
         ReadTimeout:    10 * time.Second,
         WriteTimeout:   10 * time.Second,
         MaxHeaderBytes: 1 << 20,
         Handler:        s,
     }
+}
 
-    s.SetupRoutes()
+// serveUntilShutdown returns when the stop hook shuts the HTTP server down.
-
+// If it stops for any other reason, such as its port being taken, it asks fx
-    s.log.Info("http begin listen", "listenaddr", listenAddr)
+// to shut down with exit code 1.
+func (s *Server) serveUntilShutdown() {
+    s.log.Info("http begin listen", "listenaddr", s.httpServer.Addr)
     if err := s.httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
         s.log.Error("listen error", "error", err)
-        if s.cancelFunc != nil {
+        if err := s.params.Shutdowner.Shutdown(fx.ExitCode(1)); err != nil {
-            s.cancelFunc()
+            s.log.Error("shutdown request failed", "error", err)
         }
     }
 }
@@ -292,43 +301,30 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 ## Signal Handling and Graceful Shutdown
 
+fx owns SIGINT, SIGTERM and the exit code. `Run()` in `main` waits for one of
+those signals or for a call to `Shutdown()` on `fx.Shutdowner`, runs the stop
+hooks, and exits 0 after a signal, or with the code the call gave in
+`fx.ExitCode`. It exits 1 instead when a start hook or a stop hook returns an
+error; when a start hook fails, fx first runs the stop hooks of everything
+already started. No other code calls `signal.Notify` or `os.Exit`: the listen
+error above asks fx to shut down with `fx.ExitCode(1)`, and a Sentry start
+failure is returned from the start hook. Each component releases its own
+resources in its own stop hook, which fx runs in the reverse order of start.
+
 ```go
-func (s *Server) serve() int {
+// cleanShutdown is the server's stop hook. It fails when requests are still
-    s.ctx, s.cancelFunc = context.WithCancel(context.Background())
+// running after 5 seconds.
-
+func (s *Server) cleanShutdown(ctx context.Context) error {
-    // Signal watcher
+    ctxShutdown, shutdownCancel := context.WithTimeout(ctx, 5*time.Second)
-    go func() {
+    defer shutdownCancel()
-        c := make(chan os.Signal, 1)
+    err := s.httpServer.Shutdown(ctxShutdown)
-        signal.Ignore(syscall.SIGPIPE)
-        signal.Notify(c, os.Interrupt, syscall.SIGTERM)
-        sig := <-c
-        s.log.Info("signal received", "signal", sig)
-        if s.cancelFunc != nil {
-            s.cancelFunc()
-        }
-    }()
-
-    go s.serveUntilShutdown()
-
-    for range s.ctx.Done() {
-    }
-    s.cleanShutdown()
-    return s.exitCode
-}
-
-func (s *Server) cleanShutdown() {
-    s.exitCode = 0
-    ctxShutdown, shutdownCancel := context.WithTimeout(context.Background(), 5*time.Second)
-    if err := s.httpServer.Shutdown(ctxShutdown); err != nil {
-        s.log.Error("server clean shutdown failed", "error", err)
-    }
-    if shutdownCancel != nil {
-        shutdownCancel()
-    }
-    s.cleanupForExit()
     if s.sentryEnabled {
         sentry.Flush(2 * time.Second)
     }
+    if err != nil {
+        return fmt.Errorf("http server shutdown: %w", err)
+    }
+    return nil
 }
 ```
 
@@ -1160,11 +1156,11 @@ s.router.Get("/.well-known/healthcheck", s.h.HandleHealthCheck())
 Sentry is conditionally enabled based on `SENTRY_DSN` environment variable:
 
 ```go
-func (s *Server) enableSentry() {
+func (s *Server) enableSentry() error {
     s.sentryEnabled = false
 
     if s.params.Config.SentryDSN == "" {
-        return
+        return nil
     }
 
     err := sentry.Init(sentry.ClientOptions{
@@ -1172,15 +1168,17 @@ func (s *Server) enableSentry() {
         Release: fmt.Sprintf("%s-%s", s.params.Globals.Appname, s.params.Globals.Version),
     })
     if err != nil {
-        s.log.Error("sentry init failure", "error", err)
+        return fmt.Errorf("sentry init failure: %w", err)
-        os.Exit(1)
-        return
     }
     s.log.Info("sentry error reporting activated")
     s.sentryEnabled = true
+    return nil
 }
 ```
 
+The server's start hook calls `enableSentry()` and returns its error, so a DSN
+Sentry rejects stops startup and fx exits 1.
+
 Sentry middleware with repanic (bubbles panics to chi's Recoverer):
 
 ```go
@@ -1192,7 +1190,7 @@ if s.sentryEnabled {
 }
 ```
 
-Flush Sentry on shutdown:
+Flush Sentry in the server's stop hook, `cleanShutdown()`:
 
 ```go
 if s.sentryEnabled {

prompts/NEW_REPO_CHECKLIST.md

@@ -54,6 +54,9 @@ Template files can be fetched from:
 - [ ] `LICENSE` file matching the chosen license
 - [ ] `REPO_POLICIES.md` — fetch from
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/REPO_POLICIES.md`
+- [ ] Guidance for coding agents, if the repo has any, is one `AGENTS.md` at the
+      root — never a file or directory named after one agent tool, such as
+      `CLAUDE.md` or `.claude/`, and never separate memory files
 - [ ] `Dockerfile` and `.dockerignore` — fetch `.dockerignore` from
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/.dockerignore`
     - Extend `.dockerignore` with the repo's own host-built artifacts, giving
@@ -68,10 +71,15 @@ 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` and each submodule's
+      into the build context. It keeps out every git `config` at any depth
-      `config` under `.git/modules/` at any depth (`.git/modules/**/config`),
+      (`**/.git/config`, `**/.git/modules/**/config`): the repository's own,
-      which `git describe` does not need and which can hold a credential: a
+      each submodule's under `.git/modules/`, and that of a submodule keeping
-      password in a remote URL, or the token the CI checkout step stores there.
+      its own `.git` directory. `git describe` does not need them, and each can
+      hold a credential: a password in a remote URL, or the token the CI
+      checkout step stores there. A submodule whose name has a `config` segment
+      (`config`, `deploy/config`, `config/lib`) loses its whole git directory to
+      `**/.git/modules/**/config`, and Go's version stamping then fails the
+      build: give it a name without that segment (`git submodule add --name`).
       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
@@ -116,8 +124,10 @@ are thin shims calling them. Model scripts:
 - [ ] `script/bootstrap` / `make bootstrap` — installs all dependencies,
       idempotently, assuming nothing (pkg manager detection nix/apt/brew/apk;
       node used if present, else pinned version via nvm from a hash-verified
-      archive; pinned yarn via corepack); Dockerfile runs it instead of inline
+      archive; pinned yarn via corepack); a non-server repo's development
-      installs
+      environment stage runs it instead of inline installs; a gate phase or the
+      build stage installs what its base image lacks either inline or by running
+      it
 - [ ] `script/setup` / `make setup` — readies a fresh clone: runs `bootstrap`,
       then `install-precommit`, plus repo-specific init
 - [ ] `script/test` / `make test` — `docker build --no-cache --target test .`,

prompts/REPO_POLICIES.md

@@ -104,10 +104,14 @@ style conventions are in separate documents:
   `lint` phase and a `test` phase, with the final stage depending on both so the
   image cannot be built unless they pass. For non-server repos the final stage
   brings up a development environment; for server repos it is the runtime image.
-  Dockerfiles install development prerequisites by running `script/bootstrap`
+  The gate phases and the build stage start from their pinned base images and
-  rather than duplicating installs inline; COPY `script/` and the dependency
+  install what those images lack either inline, as the canonical Go `Dockerfile`
-  manifests (`package.json` + `yarn.lock`, `go.mod` + `go.sum`, etc.) before
+  below does for `git`, or by running `script/bootstrap`, as the `prompts`
-  running it.
+  repo's own `Dockerfile` does for its yarn packages. The development
+  environment stage installs development prerequisites by running
+  `script/bootstrap` rather than duplicating its installs inline. A stage that
+  runs `script/bootstrap` COPYs `script/` and the dependency manifests
+  (`package.json` + `yarn.lock`, `go.mod` + `go.sum`, etc.) before running it.
 
 - **Linting and testing run in Docker, as phases of the `Dockerfile`.** There is
   no separate lint file. `script/lint` and `script/test` each build one phase
@@ -156,6 +160,9 @@ style conventions are in separate documents:
   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
@@ -236,13 +243,28 @@ style conventions are in separate documents:
       (e.g. a web frontend compiled in a separate stage), the lint phase must
       create placeholder files so the embed directives resolve. Example:
       `RUN mkdir -p web/dist && touch web/dist/index.html web/dist/style.css`.
-    - If the project requires CGO or system libraries for linting (e.g.
+    - If the project requires CGO or system libraries for linting, install them
-      `vips-dev`), install them in the lint phase with `apk add`.
+      in the lint phase. The `golangci/golangci-lint` image is Debian-based and
-    - `.dockerignore` lets `.git` into the build context. It keeps out
+      has no `apk`, so install with `apt-get` under the Debian package name
-      `.git/config` and each submodule's `config` under `.git/modules/` at any
+      (`libvips-dev`, where alpine says `vips-dev`), and delete the package
-      depth (`.git/modules/**/config`), which `git describe` does not need and
+      lists in the same `RUN`, so the layer does not keep them:
-      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
+        ```dockerfile
+        RUN apt-get update \
+            && apt-get install -y --no-install-recommends libvips-dev \
+            && rm -rf /var/lib/apt/lists/*
+        ```
+
+    - `.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, each submodule's under `.git/modules/`, and that of a
+      submodule keeping its own `.git` directory. `git describe` does not need
+      them, and each can hold a credential: a password in a remote URL, or the
+      token the CI checkout step stores there. A submodule whose name has a
+      `config` segment (`config`, `deploy/config`, `config/lib`) loses its whole
+      git directory to `**/.git/modules/**/config`, and Go's version stamping
+      then fails the build: give it a name without that segment
+      (`git submodule add --name`). 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
@@ -264,7 +286,12 @@ style conventions are in separate documents:
   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.
+  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.
 
 - Use platform-standard formatters: `black` for Python, `prettier` for
   JS/CSS/Markdown/HTML, `go fmt` for Go. Always use default configuration with
@@ -317,17 +344,19 @@ 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:
 
@@ -493,6 +522,11 @@ 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).
 
@@ -605,10 +639,10 @@ style conventions are in separate documents:
   settings.
 
 - Avoid putting files in the repo root unless necessary. Root should contain
-  only project-level config files (`README.md`, `Makefile`, `Dockerfile`,
+  only project-level config files (`README.md`, `AGENTS.md`, `Makefile`,
-  `LICENSE`, `.gitignore`, `.editorconfig`, `REPO_POLICIES.md`, and
+  `Dockerfile`, `LICENSE`, `.gitignore`, `.editorconfig`, `REPO_POLICIES.md`,
-  language-specific config). Everything else goes in a subdirectory. Canonical
+  and language-specific config). Everything else goes in a subdirectory.
-  subdirectory names:
+  Canonical subdirectory names:
     - `bin/` — executable scripts and tools
     - `cmd/` — Go command entrypoints; thin only: one `main.go` per binary whose
       body is a single call into `internal/` or `pkg/`, no project logic in
@@ -639,3 +673,7 @@ style conventions are in separate documents:
     - Go: `go.mod`, `go.sum`, `.golangci.yml`
     - JS: `package.json`, `yarn.lock`, `.prettierrc`, `.prettierignore`
     - Python: `pyproject.toml`
+
+- Guidance for coding agents lives in one `AGENTS.md` at the repository root. It
+  is never committed under a file or directory named after one agent tool, such
+  as `CLAUDE.md` or `.claude/`, and never split into separate memory files.