From 2df85b7731d06da2476aacc6c41cf2aac6601c83 Mon Sep 17 00:00:00 2001
From: Greg Gardner <greg@bah.org>
Date: Wed, 15 Jul 2026 02:10:49 -0700
Subject: [PATCH 1/5] chore: normalize commit messages

Nightshift-Task: commit-normalize
Nightshift-Ref: https://github.com/marcus/nightshift
---
 .githooks/commit-msg                |   5 +
 .githooks/pre-commit                |   5 +
 Makefile                            |  17 ++--
 README.md                           |  37 ++++++-
 scripts/normalize-commit-message.sh | 148 ++++++++++++++++++++++++++++
 tests/commit-message-normalizer.sh  | 146 +++++++++++++++++++++++++++
 6 files changed, 349 insertions(+), 9 deletions(-)
 create mode 100755 .githooks/commit-msg
 create mode 100755 .githooks/pre-commit
 create mode 100755 scripts/normalize-commit-message.sh
 create mode 100755 tests/commit-message-normalizer.sh

diff --git a/.githooks/commit-msg b/.githooks/commit-msg
new file mode 100755
index 0000000..93d9b70
--- /dev/null
+++ b/.githooks/commit-msg
@@ -0,0 +1,5 @@
+#!/bin/sh
+set -eu
+
+repo_root=$(git rev-parse --show-toplevel)
+exec "$repo_root/scripts/normalize-commit-message.sh" "$@"
diff --git a/.githooks/pre-commit b/.githooks/pre-commit
new file mode 100755
index 0000000..a02f0f3
--- /dev/null
+++ b/.githooks/pre-commit
@@ -0,0 +1,5 @@
+#!/bin/sh
+set -eu
+
+repo_root=$(git rev-parse --show-toplevel)
+exec "$repo_root/scripts/pre-commit.sh" "$@"
diff --git a/Makefile b/Makefile
index 088be01..10e4ec9 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: build test test-verbose test-race coverage coverage-html lint clean deps check install calibrate-providers install-hooks help
+.PHONY: build test test-commit-message test-verbose test-race coverage coverage-html lint clean deps check install calibrate-providers install-hooks help
 
 # Binary name
 BINARY=nightshift
@@ -18,9 +18,13 @@ calibrate-providers:
 	go run ./cmd/provider-calibration --repo "$$(pwd)" --codex-originator codex_cli_rs --min-user-turns 2
 
 # Run all tests
-test:
+test: test-commit-message
 	go test ./...
 
+# Run commit-message hook regression tests
+test-commit-message:
+	./tests/commit-message-normalizer.sh
+
 # Run tests with verbose output
 test-verbose:
 	go test -v ./...
@@ -65,6 +69,7 @@ help:
 	@echo "Available targets:"
 	@echo "  build         - Build the binary"
 	@echo "  test          - Run all tests"
+	@echo "  test-commit-message - Run commit-message hook regression tests"
 	@echo "  test-verbose  - Run tests with verbose output"
 	@echo "  test-race     - Run tests with race detection"
 	@echo "  coverage      - Run tests with coverage report"
@@ -75,10 +80,10 @@ help:
 	@echo "  check         - Run tests and lint"
 	@echo "  install       - Build and install to Go bin directory"
 	@echo "  calibrate-providers - Compare local Claude/Codex session usage for calibration"
-	@echo "  install-hooks  - Install git pre-commit hook"
+	@echo "  install-hooks  - Enable repository-managed git hooks"
 	@echo "  help          - Show this help"
 
-# Install git pre-commit hook
+# Enable repository-managed git hooks
 install-hooks:
-	@ln -sf ../../scripts/pre-commit.sh .git/hooks/pre-commit
-	@echo "✓ pre-commit hook installed (.git/hooks/pre-commit → scripts/pre-commit.sh)"
+	@git config core.hooksPath .githooks
+	@echo "✓ repository hooks enabled (.githooks)"
diff --git a/README.md b/README.md
index b7c2b5d..2e780f9 100644
--- a/README.md
+++ b/README.md
@@ -301,19 +301,50 @@ Each task has a default cooldown interval to prevent the same task from running
 
 ## Development
 
-### Pre-commit hooks
+### Git hooks and commit messages
 
-Install the git pre-commit hook to catch formatting and vet issues before pushing:
+Enable the repository-managed hooks before committing:
 
 ```bash
 make install-hooks
+# Equivalent command:
+git config core.hooksPath .githooks
 ```
 
-This symlinks `scripts/pre-commit.sh` into `.git/hooks/pre-commit`. The hook runs:
+The `pre-commit` hook runs:
 - **gofmt** - flags any staged `.go` files that need formatting
 - **go vet** - catches common correctness issues
 - **go build** - ensures the project compiles
 
+The `commit-msg` hook normalizes and validates Conventional Commit subjects in
+the `type(scope)!: summary` format. The scope and `!` marker are optional. The
+supported types are `build`, `chore`, `ci`, `docs`, `feat`, `fix`, `perf`,
+`refactor`, `style`, and `test`.
+
+The normalizer lowercases supported types, removes spacing around the optional
+scope and breaking-change marker, collapses repeated subject whitespace, trims
+leading and trailing blank lines, and removes trailing whitespace. Message body
+paragraphs and Git trailers otherwise keep their original content.
+
+Examples:
+
+```text
+feat(run): add pause command
+fix(config)!: reject unknown provider keys
+docs: explain hook installation
+```
+
+Merge and revert messages, `fixup!`, `squash!`, and `amend!` commits, stash
+subjects, and comment-led messages generated by Git are preserved byte for byte.
+An empty message, unsupported type, missing summary, or malformed scope is
+rejected without changing the message file.
+
+Run the shell regression suite directly with:
+
+```bash
+make test-commit-message
+```
+
 To bypass in a pinch: `git commit --no-verify`
 
 ## Uninstalling
diff --git a/scripts/normalize-commit-message.sh b/scripts/normalize-commit-message.sh
new file mode 100755
index 0000000..fc02102
--- /dev/null
+++ b/scripts/normalize-commit-message.sh
@@ -0,0 +1,148 @@
+#!/bin/sh
+
+# Normalize and validate a Conventional Commit message in place.
+set -eu
+
+usage() {
+  echo "usage: $0 <commit-message-file>" >&2
+}
+
+if [ "$#" -ne 1 ]; then
+  usage
+  exit 2
+fi
+
+message_file=$1
+if [ ! -f "$message_file" ] || [ ! -r "$message_file" ] || [ ! -w "$message_file" ]; then
+  echo "commit message is not a readable, writable file: $message_file" >&2
+  exit 2
+fi
+
+# Git creates these subjects itself. Rewriting them can break merges, reverts,
+# autosquash, stashes, and interactive rebases, so preserve the entire file.
+first_line=$(awk '
+  {
+    line = $0
+    sub(/\r$/, "", line)
+    if (line !~ /^[[:space:]]*$/) {
+      sub(/^[[:space:]]+/, "", line)
+      print line
+      exit
+    }
+  }
+' "$message_file")
+
+case "$first_line" in
+  \#*|Merge\ *|Revert\ *|fixup\!\ *|squash\!\ *|amend\!\ *|WIP\ on\ *|index\ on\ *)
+    exit 0
+    ;;
+esac
+
+tmp_file=$(mktemp "${TMPDIR:-/tmp}/nightshift-commit-msg.XXXXXX") || exit 2
+cleanup() {
+  rm -f "$tmp_file"
+}
+trap cleanup 0
+trap 'exit 1' 1 2 15
+
+if ! awk '
+  function trim(value) {
+    sub(/^[[:space:]]+/, "", value)
+    sub(/[[:space:]]+$/, "", value)
+    return value
+  }
+
+  function collapse(value) {
+    value = trim(value)
+    gsub(/[[:space:]]+/, " ", value)
+    return value
+  }
+
+  function supported(value) {
+    return value == "build" || value == "chore" || value == "ci" ||
+      value == "docs" || value == "feat" || value == "fix" ||
+      value == "perf" || value == "refactor" || value == "style" ||
+      value == "test"
+  }
+
+  {
+    line = $0
+    sub(/[[:space:]]+$/, "", line)
+    lines[++count] = line
+  }
+
+  END {
+    first = 1
+    while (first <= count && lines[first] == "") {
+      first++
+    }
+
+    last = count
+    while (last >= first && lines[last] == "") {
+      last--
+    }
+
+    if (first > last) {
+      exit 1
+    }
+
+    subject = collapse(lines[first])
+    colon = index(subject, ":")
+    if (colon == 0) {
+      exit 1
+    }
+
+    header = trim(substr(subject, 1, colon - 1))
+    summary = collapse(substr(subject, colon + 1))
+    if (summary == "") {
+      exit 1
+    }
+
+    breaking = ""
+    if (header ~ /![[:space:]]*$/) {
+      sub(/![[:space:]]*$/, "", header)
+      header = trim(header)
+      breaking = "!"
+    }
+
+    open = index(header, "(")
+    scope = ""
+    if (open > 0) {
+      if (substr(header, length(header), 1) != ")") {
+        exit 1
+      }
+      type = tolower(trim(substr(header, 1, open - 1)))
+      scope = collapse(substr(header, open + 1, length(header) - open - 1))
+      if (scope == "" || scope !~ /^[[:alnum:]_.\/#-]+$/) {
+        exit 1
+      }
+    } else {
+      type = tolower(trim(header))
+      if (type ~ /[()]/) {
+        exit 1
+      }
+    }
+
+    if (!supported(type)) {
+      exit 1
+    }
+
+    normalized = type
+    if (scope != "") {
+      normalized = normalized "(" scope ")"
+    }
+    print normalized breaking ": " summary
+
+    for (i = first + 1; i <= last; i++) {
+      print lines[i]
+    }
+  }
+' "$message_file" > "$tmp_file"; then
+  cat >&2 <<'EOF'
+invalid commit subject; expected type(scope)!: summary
+supported types: build, chore, ci, docs, feat, fix, perf, refactor, style, test
+EOF
+  exit 1
+fi
+
+cat "$tmp_file" > "$message_file"
diff --git a/tests/commit-message-normalizer.sh b/tests/commit-message-normalizer.sh
new file mode 100755
index 0000000..3bf6191
--- /dev/null
+++ b/tests/commit-message-normalizer.sh
@@ -0,0 +1,146 @@
+#!/bin/sh
+set -eu
+
+repo_root=$(CDPATH= cd "$(dirname "$0")/.." && pwd)
+normalizer="$repo_root/scripts/normalize-commit-message.sh"
+hook="$repo_root/.githooks/commit-msg"
+test_dir=$(mktemp -d "${TMPDIR:-/tmp}/nightshift-commit-msg-test.XXXXXX")
+cleanup() {
+  rm -rf "$test_dir"
+}
+trap cleanup 0
+trap 'exit 1' 1 2 15
+
+tests_run=0
+
+fail() {
+  echo "not ok - $1" >&2
+  exit 1
+}
+
+assert_normalizes() {
+  name=$1
+  input=$2
+  expected=$3
+  message="$test_dir/message"
+  expected_file="$test_dir/expected"
+
+  printf '%b' "$input" > "$message"
+  printf '%b' "$expected" > "$expected_file"
+  "$normalizer" "$message" || fail "$name (normalizer failed)"
+  cmp -s "$expected_file" "$message" || {
+    diff -u "$expected_file" "$message" >&2 || true
+    fail "$name"
+  }
+  tests_run=$((tests_run + 1))
+  echo "ok - $name"
+}
+
+assert_preserved() {
+  name=$1
+  input=$2
+  assert_normalizes "$name" "$input" "$input"
+}
+
+assert_rejected() {
+  name=$1
+  input=$2
+  message="$test_dir/message"
+  original="$test_dir/original"
+
+  printf '%b' "$input" > "$message"
+  cp "$message" "$original"
+  if "$normalizer" "$message" >/dev/null 2>&1; then
+    fail "$name (unexpected success)"
+  fi
+  cmp -s "$original" "$message" || fail "$name (message changed)"
+  tests_run=$((tests_run + 1))
+  echo "ok - $name"
+}
+
+assert_normalizes \
+  "already-valid subject" \
+  'feat(cli): add status output
+' \
+  'feat(cli): add status output
+'
+
+assert_normalizes \
+  "capitalization and spacing" \
+  '
+  FEAT  ( cli ) ! :   add   status output\040\040\040
+
+' \
+  'feat(cli)!: add status output
+'
+
+assert_normalizes \
+  "scoped breaking change" \
+  'FIX (config)!:   reject unknown keys
+' \
+  'fix(config)!: reject unknown keys
+'
+
+assert_normalizes \
+  "body paragraphs and trailers" \
+  'DOCS :   explain   provider setup\040\040\040
+
+Keep  repeated  body spacing.\040\040\040
+
+Nightshift-Task: commit-normalize\040\040\040
+Nightshift-Ref: https://github.com/marcus/nightshift
+
+' \
+  'docs: explain provider setup
+
+Keep  repeated  body spacing.
+
+Nightshift-Task: commit-normalize
+Nightshift-Ref: https://github.com/marcus/nightshift
+'
+
+assert_rejected "blank input" '
+\040\040\040
+'
+assert_rejected "unsupported type" 'release: prepare 1.0
+'
+
+assert_preserved "merge message" 'Merge branch '\''main'\'' into feature\040\040\040
+
+Generated merge body.\040\040\040
+'
+assert_preserved "revert message" 'Revert "feat: remove legacy API"
+
+This reverts commit abc123.\040\040\040
+'
+assert_preserved "fixup commit" 'fixup! feat(cli): add status output\040\040\040
+'
+assert_preserved "squash commit" 'squash! fix(config): reject unknown keys\040\040\040
+'
+assert_preserved "generated rebase message" '# This is a combination of 2 commits.
+# This is the 1st commit message:
+
+feat: first message\040\040\040
+'
+
+message="$test_dir/message"
+printf '%b' ' CHORE :   normalize messages\040
+' > "$message"
+"$hook" "$message" || fail "commit-msg hook"
+printf '%s' 'chore: normalize messages
+' > "$test_dir/expected"
+cmp -s "$test_dir/expected" "$message" || fail "commit-msg hook"
+if "$hook" "$test_dir/missing" >/dev/null 2>&1; then
+  fail "commit-msg hook propagates failures"
+fi
+tests_run=$((tests_run + 2))
+echo "ok - commit-msg hook"
+echo "ok - commit-msg hook propagates failures"
+
+cp "$message" "$test_dir/once"
+"$normalizer" "$message" || fail "idempotence (second run failed)"
+cmp -s "$test_dir/once" "$message" || fail "idempotence"
+tests_run=$((tests_run + 1))
+echo "ok - idempotence"
+
+echo "$tests_run tests passed"

From 2e6f2ac4819b77cc9f1c21710096a80498116ed2 Mon Sep 17 00:00:00 2001
From: Greg Gardner <greg@bah.org>
Date: Wed, 15 Jul 2026 02:28:08 -0700
Subject: [PATCH 2/5] fix: preserve configured Git comments

Nightshift-Task: commit-normalize
Nightshift-Ref: https://github.com/marcus/nightshift
---
 README.md                           |  2 ++
 scripts/normalize-commit-message.sh | 24 ++++++++++++++++++-
 tests/commit-message-normalizer.sh  | 36 +++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 2e780f9..3935b29 100644
--- a/README.md
+++ b/README.md
@@ -336,6 +336,8 @@ docs: explain hook installation
 
 Merge and revert messages, `fixup!`, `squash!`, and `amend!` commits, stash
 subjects, and comment-led messages generated by Git are preserved byte for byte.
+Comment-led messages honor Git's configured `core.commentChar` or
+`core.commentString` prefix, falling back to Git's default `#` prefix.
 An empty message, unsupported type, missing summary, or malformed scope is
 rejected without changing the message file.
 
diff --git a/scripts/normalize-commit-message.sh b/scripts/normalize-commit-message.sh
index fc02102..8cdfe19 100755
--- a/scripts/normalize-commit-message.sh
+++ b/scripts/normalize-commit-message.sh
@@ -32,8 +32,30 @@ first_line=$(awk '
   }
 ' "$message_file")
 
+comment_prefix=$(
+  git config --get-regexp '^core\.comment(char|string)$' 2>/dev/null |
+    awk '
+      {
+        sub(/^[^[:space:]]+[[:space:]]+/, "")
+        prefix = $0
+      }
+      END { print prefix }
+    '
+)
+case "$comment_prefix" in
+  ""|auto)
+    comment_prefix="#"
+    ;;
+esac
+
+case "$first_line" in
+  "$comment_prefix"*)
+    exit 0
+    ;;
+esac
+
 case "$first_line" in
-  \#*|Merge\ *|Revert\ *|fixup\!\ *|squash\!\ *|amend\!\ *|WIP\ on\ *|index\ on\ *)
+  Merge\ *|Revert\ *|fixup\!\ *|squash\!\ *|amend\!\ *|WIP\ on\ *|index\ on\ *)
     exit 0
     ;;
 esac
diff --git a/tests/commit-message-normalizer.sh b/tests/commit-message-normalizer.sh
index 3bf6191..b08a14c 100755
--- a/tests/commit-message-normalizer.sh
+++ b/tests/commit-message-normalizer.sh
@@ -42,6 +42,28 @@ assert_preserved() {
   assert_normalizes "$name" "$input" "$input"
 }
 
+assert_preserved_with_comment_prefix() {
+  name=$1
+  comment_key=$2
+  comment_prefix=$3
+  input=$4
+  message="$test_dir/message"
+  expected_file="$test_dir/expected"
+
+  printf '%b' "$input" > "$message"
+  printf '%b' "$input" > "$expected_file"
+  GIT_CONFIG_COUNT=1 \
+    GIT_CONFIG_KEY_0="core.$comment_key" \
+    GIT_CONFIG_VALUE_0="$comment_prefix" \
+    "$normalizer" "$message" || fail "$name (normalizer failed)"
+  cmp -s "$expected_file" "$message" || {
+    diff -u "$expected_file" "$message" >&2 || true
+    fail "$name"
+  }
+  tests_run=$((tests_run + 1))
+  echo "ok - $name"
+}
+
 assert_rejected() {
   name=$1
   input=$2
@@ -122,6 +144,20 @@ assert_preserved "generated rebase message" '# This is a combination of 2 commit
 
 feat: first message\040\040\040
 '
+assert_preserved_with_comment_prefix \
+  "generated message with configured comment character" \
+  "commentChar" \
+  ";" \
+  '; Please enter the commit message for your changes.\040\040\040
+; Lines starting with '\'';'\'' will be ignored.
+'
+assert_preserved_with_comment_prefix \
+  "generated message with configured comment string" \
+  "commentString" \
+  "//" \
+  '// Please enter the commit message for your changes.\040\040\040
+// Lines starting with '\''//'\'' will be ignored.
+'
 
 message="$test_dir/message"
 printf '%b' ' CHORE :   normalize messages\040

From e7b9137cfaf5a350d03aa1fbbc1d3aed0ab35783 Mon Sep 17 00:00:00 2001
From: Greg Gardner <greg@bah.org>
Date: Wed, 22 Jul 2026 02:07:42 -0700
Subject: [PATCH 3/5] chore: add safe hook installer

Nightshift-Task: commit-normalize
Nightshift-Ref: https://github.com/marcus/nightshift
---
 Makefile                           |  3 +--
 README.md                          | 19 ++++++++++++--
 scripts/install-git-hooks.sh       | 15 +++++++++++
 tests/commit-message-normalizer.sh | 40 ++++++++++++++++++++++++++++++
 4 files changed, 73 insertions(+), 4 deletions(-)
 create mode 100755 scripts/install-git-hooks.sh

diff --git a/Makefile b/Makefile
index 10e4ec9..b19b178 100644
--- a/Makefile
+++ b/Makefile
@@ -85,5 +85,4 @@ help:
 
 # Enable repository-managed git hooks
 install-hooks:
-	@git config core.hooksPath .githooks
-	@echo "✓ repository hooks enabled (.githooks)"
+	@./scripts/install-git-hooks.sh
diff --git a/README.md b/README.md
index 3935b29..7738fd5 100644
--- a/README.md
+++ b/README.md
@@ -307,10 +307,13 @@ Enable the repository-managed hooks before committing:
 
 ```bash
 make install-hooks
-# Equivalent command:
-git config core.hooksPath .githooks
+# Equivalent:
+./scripts/install-git-hooks.sh
 ```
 
+The installer writes `core.hooksPath` to this repository's local `.git/config`.
+It does not change system- or user-level Git configuration.
+
 The `pre-commit` hook runs:
 - **gofmt** - flags any staged `.go` files that need formatting
 - **go vet** - catches common correctness issues
@@ -347,6 +350,18 @@ Run the shell regression suite directly with:
 make test-commit-message
 ```
 
+To check and preview normalization for a message manually:
+
+```bash
+message_file=$(mktemp)
+printf '%s\n' ' FEAT (cli) :   add status output ' > "$message_file"
+./scripts/normalize-commit-message.sh "$message_file" && cat "$message_file"
+rm "$message_file"
+```
+
+The command exits nonzero and leaves the file unchanged when the subject cannot
+be normalized unambiguously.
+
 To bypass in a pinch: `git commit --no-verify`
 
 ## Uninstalling
diff --git a/scripts/install-git-hooks.sh b/scripts/install-git-hooks.sh
new file mode 100755
index 0000000..35d9a7f
--- /dev/null
+++ b/scripts/install-git-hooks.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# Enable this repository's version-controlled hooks without changing global Git
+# configuration.
+set -eu
+
+repo_root=$(CDPATH= cd "$(dirname "$0")/.." && pwd)
+
+if ! git -C "$repo_root" rev-parse --is-inside-work-tree >/dev/null 2>&1; then
+  echo "not a Git worktree: $repo_root" >&2
+  exit 1
+fi
+
+git -C "$repo_root" config --local core.hooksPath .githooks
+echo "repository hooks enabled (.githooks)"
diff --git a/tests/commit-message-normalizer.sh b/tests/commit-message-normalizer.sh
index b08a14c..dbacb31 100755
--- a/tests/commit-message-normalizer.sh
+++ b/tests/commit-message-normalizer.sh
@@ -4,6 +4,7 @@ set -eu
 repo_root=$(CDPATH= cd "$(dirname "$0")/.." && pwd)
 normalizer="$repo_root/scripts/normalize-commit-message.sh"
 hook="$repo_root/.githooks/commit-msg"
+installer="$repo_root/scripts/install-git-hooks.sh"
 test_dir=$(mktemp -d "${TMPDIR:-/tmp}/nightshift-commit-msg-test.XXXXXX")
 cleanup() {
   rm -rf "$test_dir"
@@ -121,11 +122,30 @@ Nightshift-Task: commit-normalize
 Nightshift-Ref: https://github.com/marcus/nightshift
 '
 
+assert_normalizes \
+  "Git comments after subject" \
+  ' CHORE :   normalize messages
+
+# Please enter the commit message for your changes.
+# Lines starting with '\''#'\'' will be ignored.
+' \
+  'chore: normalize messages
+
+# Please enter the commit message for your changes.
+# Lines starting with '\''#'\'' will be ignored.
+'
+
 assert_rejected "blank input" '
 \040\040\040
 '
 assert_rejected "unsupported type" 'release: prepare 1.0
 '
+assert_rejected "missing separator" 'feat add status output
+'
+assert_rejected "empty scope" 'feat(): add status output
+'
+assert_rejected "missing summary" 'feat(cli):
+'
 
 assert_preserved "merge message" 'Merge branch '\''main'\'' into feature\040\040\040
 
@@ -179,4 +199,24 @@ cmp -s "$test_dir/once" "$message" || fail "idempotence"
 tests_run=$((tests_run + 1))
 echo "ok - idempotence"
 
+installer_repo="$test_dir/installer-repo"
+mkdir -p "$installer_repo/scripts" "$installer_repo/.githooks"
+cp "$installer" "$installer_repo/scripts/install-git-hooks.sh"
+git -C "$installer_repo" init -q
+global_config="$test_dir/global-gitconfig"
+GIT_CONFIG_GLOBAL="$global_config" git config --global core.hooksPath /user/hooks
+GIT_CONFIG_GLOBAL="$global_config" "$installer_repo/scripts/install-git-hooks.sh" >/dev/null ||
+  fail "hook installer"
+installed_path=$(GIT_CONFIG_GLOBAL="$global_config" git -C "$installer_repo" config --local --get core.hooksPath)
+[ "$installed_path" = ".githooks" ] || fail "hook installer writes local config"
+global_path=$(GIT_CONFIG_GLOBAL="$global_config" git config --global --get core.hooksPath)
+[ "$global_path" = "/user/hooks" ] || fail "hook installer preserves user config"
+GIT_CONFIG_GLOBAL="$global_config" "$installer_repo/scripts/install-git-hooks.sh" >/dev/null ||
+  fail "hook installer idempotence"
+tests_run=$((tests_run + 4))
+echo "ok - hook installer"
+echo "ok - hook installer writes local config"
+echo "ok - hook installer preserves user config"
+echo "ok - hook installer idempotence"
+
 echo "$tests_run tests passed"

From 85be299cd21d82a1b220a9c1f311858758eb2c5e Mon Sep 17 00:00:00 2001
From: Greg Gardner <greg@bah.org>
Date: Wed, 22 Jul 2026 02:21:08 -0700
Subject: [PATCH 4/5] fix: harden commit hook setup

Nightshift-Task: commit-normalize
Nightshift-Ref: https://github.com/marcus/nightshift
---
 README.md                           | 16 +++++---
 scripts/install-git-hooks.sh        | 13 +++++++
 scripts/normalize-commit-message.sh | 18 +++++++--
 tests/commit-message-normalizer.sh  | 57 +++++++++++++++++++++++++++--
 4 files changed, 91 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index 7738fd5..97f872c 100644
--- a/README.md
+++ b/README.md
@@ -312,7 +312,10 @@ make install-hooks
 ```
 
 The installer writes `core.hooksPath` to this repository's local `.git/config`.
-It does not change system- or user-level Git configuration.
+It does not change system- or user-level Git configuration. If the repository
+already has a different local hooks path, the installer stops without changing
+it; merge those hooks into `.githooks` or remove the local setting before
+installing.
 
 The `pre-commit` hook runs:
 - **gofmt** - flags any staged `.go` files that need formatting
@@ -338,11 +341,12 @@ docs: explain hook installation
 ```
 
 Merge and revert messages, `fixup!`, `squash!`, and `amend!` commits, stash
-subjects, and comment-led messages generated by Git are preserved byte for byte.
-Comment-led messages honor Git's configured `core.commentChar` or
-`core.commentString` prefix, falling back to Git's default `#` prefix.
-An empty message, unsupported type, missing summary, or malformed scope is
-rejected without changing the message file.
+subjects, and Git's comment-led combined-commit messages are preserved byte for
+byte. Combined-commit detection honors Git's configured `core.commentChar` or
+`core.commentString` prefix, falling back to Git's default `#` prefix. Other
+comment-led subjects are validated normally, so a manual subject such as
+`# invalid subject` is rejected. An empty message, unsupported type, missing
+summary, or malformed scope is rejected without changing the message file.
 
 Run the shell regression suite directly with:
 
diff --git a/scripts/install-git-hooks.sh b/scripts/install-git-hooks.sh
index 35d9a7f..76daec2 100755
--- a/scripts/install-git-hooks.sh
+++ b/scripts/install-git-hooks.sh
@@ -11,5 +11,18 @@ if ! git -C "$repo_root" rev-parse --is-inside-work-tree >/dev/null 2>&1; then
   exit 1
 fi
 
+if existing_hooks_path=$(git -C "$repo_root" config --local --get core.hooksPath 2>/dev/null); then
+  if [ "$existing_hooks_path" != ".githooks" ]; then
+    cat >&2 <<EOF
+repository already uses core.hooksPath=$existing_hooks_path
+merge those hooks into .githooks or remove the local setting, then rerun this installer
+EOF
+    exit 1
+  fi
+
+  echo "repository hooks already enabled (.githooks)"
+  exit 0
+fi
+
 git -C "$repo_root" config --local core.hooksPath .githooks
 echo "repository hooks enabled (.githooks)"
diff --git a/scripts/normalize-commit-message.sh b/scripts/normalize-commit-message.sh
index 8cdfe19..127da61 100755
--- a/scripts/normalize-commit-message.sh
+++ b/scripts/normalize-commit-message.sh
@@ -48,9 +48,21 @@ case "$comment_prefix" in
     ;;
 esac
 
-case "$first_line" in
-  "$comment_prefix"*)
-    exit 0
+comment_text=${first_line#"$comment_prefix"}
+combination_prefix=' This is a combination of '
+case "$comment_text" in
+  "$combination_prefix"*' commits.')
+    commit_count=${comment_text#"$combination_prefix"}
+    commit_count=${commit_count%' commits.'}
+    case "$commit_count" in
+      ""|*[!0-9]*)
+        ;;
+      *)
+        if [ "$commit_count" -ge 2 ]; then
+          exit 0
+        fi
+        ;;
+    esac
     ;;
 esac
 
diff --git a/tests/commit-message-normalizer.sh b/tests/commit-message-normalizer.sh
index dbacb31..a64e211 100755
--- a/tests/commit-message-normalizer.sh
+++ b/tests/commit-message-normalizer.sh
@@ -81,6 +81,27 @@ assert_rejected() {
   echo "ok - $name"
 }
 
+assert_rejected_with_comment_prefix() {
+  name=$1
+  comment_key=$2
+  comment_prefix=$3
+  input=$4
+  message="$test_dir/message"
+  original="$test_dir/original"
+
+  printf '%b' "$input" > "$message"
+  cp "$message" "$original"
+  if GIT_CONFIG_COUNT=1 \
+    GIT_CONFIG_KEY_0="core.$comment_key" \
+    GIT_CONFIG_VALUE_0="$comment_prefix" \
+    "$normalizer" "$message" >/dev/null 2>&1; then
+    fail "$name (unexpected success)"
+  fi
+  cmp -s "$original" "$message" || fail "$name (message changed)"
+  tests_run=$((tests_run + 1))
+  echo "ok - $name"
+}
+
 assert_normalizes \
   "already-valid subject" \
   'feat(cli): add status output
@@ -146,6 +167,16 @@ assert_rejected "empty scope" 'feat(): add status output
 '
 assert_rejected "missing summary" 'feat(cli):
 '
+assert_rejected "manual comment subject" '# invalid manual subject
+'
+assert_rejected "lookalike generated comment subject" '# This is a combination of banana commits.
+'
+assert_rejected_with_comment_prefix \
+  "manual subject with configured comment string" \
+  "commentString" \
+  "//" \
+  '// invalid manual subject
+'
 
 assert_preserved "merge message" 'Merge branch '\''main'\'' into feature\040\040\040
 
@@ -168,15 +199,19 @@ assert_preserved_with_comment_prefix \
   "generated message with configured comment character" \
   "commentChar" \
   ";" \
-  '; Please enter the commit message for your changes.\040\040\040
-; Lines starting with '\'';'\'' will be ignored.
+  '; This is a combination of 2 commits.
+; This is the 1st commit message:
+
+feat: first message\040\040\040
 '
 assert_preserved_with_comment_prefix \
   "generated message with configured comment string" \
   "commentString" \
   "//" \
-  '// Please enter the commit message for your changes.\040\040\040
-// Lines starting with '\''//'\'' will be ignored.
+  '// This is a combination of 2 commits.
+// This is the 1st commit message:
+
+feat: first message\040\040\040
 '
 
 message="$test_dir/message"
@@ -219,4 +254,18 @@ echo "ok - hook installer writes local config"
 echo "ok - hook installer preserves user config"
 echo "ok - hook installer idempotence"
 
+conflict_repo="$test_dir/conflict-repo"
+mkdir -p "$conflict_repo/scripts" "$conflict_repo/.githooks"
+cp "$installer" "$conflict_repo/scripts/install-git-hooks.sh"
+git -C "$conflict_repo" init -q
+git -C "$conflict_repo" config --local core.hooksPath .custom-hooks
+if "$conflict_repo/scripts/install-git-hooks.sh" >/dev/null 2>&1; then
+  fail "hook installer rejects conflicting local config"
+fi
+conflict_path=$(git -C "$conflict_repo" config --local --get core.hooksPath)
+[ "$conflict_path" = ".custom-hooks" ] || fail "hook installer preserves conflicting local config"
+tests_run=$((tests_run + 2))
+echo "ok - hook installer rejects conflicting local config"
+echo "ok - hook installer preserves conflicting local config"
+
 echo "$tests_run tests passed"

From 25b0da7863cf84f673dcf85258ec9a2afeaaaeff Mon Sep 17 00:00:00 2001
From: Greg Gardner <greg@bah.org>
Date: Wed, 22 Jul 2026 02:35:35 -0700
Subject: [PATCH 5/5] test: isolate commit hook regressions

Nightshift-Task: commit-normalize
Nightshift-Ref: https://github.com/marcus/nightshift
---
 tests/commit-message-normalizer.sh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tests/commit-message-normalizer.sh b/tests/commit-message-normalizer.sh
index a64e211..7c92e78 100755
--- a/tests/commit-message-normalizer.sh
+++ b/tests/commit-message-normalizer.sh
@@ -12,6 +12,17 @@ cleanup() {
 trap cleanup 0
 trap 'exit 1' 1 2 15
 
+# Keep the default-prefix fixtures independent of system, user, repository, and
+# inherited command-scope Git configuration. Individual tests override this
+# command-scope value when exercising core.commentChar or core.commentString.
+GIT_CONFIG_NOSYSTEM=1
+GIT_CONFIG_GLOBAL="$test_dir/empty-gitconfig"
+GIT_CONFIG_COUNT=1
+GIT_CONFIG_KEY_0=core.commentChar
+GIT_CONFIG_VALUE_0='#'
+export GIT_CONFIG_NOSYSTEM GIT_CONFIG_GLOBAL GIT_CONFIG_COUNT
+export GIT_CONFIG_KEY_0 GIT_CONFIG_VALUE_0
+
 tests_run=0
 
 fail() {