From 4ce0814b1481bfdb67878deb97e9f1f73a09b4d5 Mon Sep 17 00:00:00 2001
From: clawbot <35+clawbot@noreply.example.org>
Date: Fri, 2 Oct 2026 04:26:40 +0200
Subject: [PATCH] Stamp the git tag or short commit in a plain docker build
 (closes #86)

The builder stage now has git and takes the version from the VERSION
build argument when one is given, otherwise from `git describe --tags
--always` of the repo's .git, copied to /git so go build does not see
it. A version that still comes out empty, dev or unknown fails the
build. ARG VERSION has no default. .dockerignore keeps .git/config out
of the build context, and the comments in script/docker and
script/cibuild no longer say .git is excluded.

Model: opus-5-5
---
 .dockerignore  |  3 +++
 Dockerfile     | 19 ++++++++++++++++---
 script/cibuild |  5 ++---
 script/docker  |  5 ++---
 4 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/.dockerignore b/.dockerignore
index 416281f..033ab7b 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -4,3 +4,6 @@ tmp
 .DS_Store
 *.log
 .claude
+
+# .git is sent so the build can stamp the version, without its config.
+.git/config
diff --git a/Dockerfile b/Dockerfile
index 1504805..4203274 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -20,7 +20,7 @@ RUN make lint
 # golang:1.25-alpine (2026-02-27)
 FROM golang:1.25-alpine@sha256:f6751d823c26342f9506c03797d2527668d095b0a15f1862cddb4d927a7a4ced AS builder
 
-RUN apk add --no-cache make
+RUN apk add --no-cache git make
 
 WORKDIR /src
 
@@ -40,8 +40,21 @@ RUN make test
 # CGO_ENABLED=0 go build -trimpath -ldflags "-s -w -X main.Version=..."
 # That script reads VERSION from the environment, so it is handed over
 # there rather than as a make variable.
-ARG VERSION=dev
-RUN VERSION="${VERSION}" make build
+#
+# The version is the VERSION build argument when one is given, otherwise
+# `git describe --tags --always` of the repo's .git: the tag on a tagged
+# commit, tag-N-gHASH on a commit after one, the short commit when no
+# tag is reachable. A version that still comes out empty, dev or unknown
+# fails the build. .git goes to /git, not /src/.git, where go build would
+# find it and record VCS details of a work tree holding only backend/.
+COPY .git /git
+ARG VERSION
+RUN version="${VERSION:-$(git --git-dir=/git describe --tags --always)}"; \
+    case "$version" in ""|dev|unknown) \
+        echo "version is '$version' although .git is present" >&2; \
+        exit 1 ;; \
+    esac; \
+    VERSION="$version" make build
 
 # Frontend stage
 # node:22-alpine as of 2026-02-22
diff --git a/script/cibuild b/script/cibuild
index 688299f..d8d3200 100755
--- a/script/cibuild
+++ b/script/cibuild
@@ -16,9 +16,8 @@ main() {
     "$SCRIPT_DIR/check"
     # Own line: a failing command substitution inside an argument does
     # not trip `set -e`, so the inline form degrades silently to an
-    # empty constant. VERSION is computed here because .dockerignore
-    # excludes .git, so `git describe` in a build stage yields an empty
-    # version without failing.
+    # empty constant. The VERSION build argument takes precedence over
+    # the version a build stage derives from the .git in the context.
     version="$(git describe --tags --always --dirty 2>/dev/null || true)"
     [ -n "$version" ] || version="unknown"
     docker build --no-cache \
diff --git a/script/docker b/script/docker
index c4688e8..07b626c 100755
--- a/script/docker
+++ b/script/docker
@@ -12,9 +12,8 @@ main() {
     cd "$ROOT"
     # Own line: a failing command substitution inside an argument does
     # not trip `set -e`, so the inline form degrades silently to an
-    # empty constant. VERSION is computed here because .dockerignore
-    # excludes .git, so `git describe` in a build stage yields an empty
-    # version without failing.
+    # empty constant. The VERSION build argument takes precedence over
+    # the version a build stage derives from the .git in the context.
     version="$(git describe --tags --always --dirty 2>/dev/null || true)"
     [ -n "$version" ] || version="unknown"
     docker build --no-cache \