Add pre-push hook with PR size warning

[Copilot]

Adds a local git pre-push hook that warns developers when a push exceeds 500 changed lines, prompting to split into smaller PRs. Hook fires on every push to any remote branch and is bypassable via git push --no-verify.

Files added

• .githooks/pr-size-check.sh — Shared hook logic: resolves base branch (origin/dev → origin/main → origin/master), filters out Xcode artifacts/configs/images, counts net line changes, and prompts if over limit
• .githooks/pre-push — Repo-specific entry point; sets EXTRA_EXCLUDES to skip IdentityCore/tests/, IdentityCore/MSIDTestsHostApp/, and scripts/, then sources the shared script
• Makefile — setup target that writes core.hooksPath = .githooks into the local git config

Activation (one-time per clone)

make setup

After this, every git push triggers the size check automatically. Developers who already have a clone need to run make setup once; new clones require the same one-time step.

Original prompt

Summary

Add a local pre-push git hook that warns developers when their changes exceed the recommended PR size (500 lines) before pushing to any remote branch.

Files to create

1. .githooks/pr-size-check.sh — Shared reusable logic (identical across all repos)

#!/bin/bash
# ============================================================
# PR Size Check — Reusable Hook Logic
#
# Do NOT call this directly. It is sourced by the pre-push hook
# with repo-specific config already set:
#
#   MAX_LINES          — line change limit (default: 500)
#   EXTRA_EXCLUDES     — bash array of additional regex patterns
# ============================================================

MAX_LINES="${MAX_LINES:-500}"

# ── Common exclusions (all repos) ────────────────────────────
COMMON_EXCLUDES=(
  "\.pbxproj$"
  "\.xcscheme$"
  "\.xcsettings$"
  "\.xcconfig$"
  "\.xctestplan$"
  "\.xcworkspace/"
  "\.xcodeproj/"
  "\.plist$"
  "\.entitlements$"
  "\.storyboard$"
  "\.xib$"
  "\.xcassets/"
  "\.modulemap$"
  "\.xcprivacy$"
  "\.ya?ml$"
  "\.lock$"
  "\.(png|jpg|jpeg|svg|pdf|icns|gif|tiff)$"
)

# ── Merge common + repo-specific exclusions ───────────────────
ALL_EXCLUDES=("${COMMON_EXCLUDES[@]}" "${EXTRA_EXCLUDES[@]}")

# ── Build grep pattern ────────────────────────────────────────
GREP_PATTERN=$(printf "|%s" "${ALL_EXCLUDES[@]}")
GREP_PATTERN="${GREP_PATTERN:1}"

# ── Resolve base branch — always origin/dev ──────────────────
BASE_BRANCH=""
for candidate in origin/dev origin/main origin/master; do
  if git show-ref --verify --quiet "refs/remotes/${candidate}"; then
    BASE_BRANCH="$candidate"
    break
  fi
done

if [ -z "$BASE_BRANCH" ]; then
  echo "ℹ️  PR size check skipped: no remote base branch found."
  exit 0
fi

# ── Get list of changed files (excluding patterns) ───────────
CHANGED_FILES=$(git diff --name-only "$BASE_BRANCH"...HEAD 2>/dev/null | grep -vE "$GREP_PATTERN")

if [ -z "$CHANGED_FILES" ]; then
  exit 0
fi

# ── Count lines changed ───────────────────────────────────────
TOTAL_LINES=$(git diff "$BASE_BRANCH"...HEAD -- $CHANGED_FILES 2>/dev/null \
  | grep -E "^\+|^-" \
  | grep -vE "^\+\+\+|^---" \
  | wc -l \
  | tr -d ' ')

# ── Warn if over limit ────────────────────────────────────────
if [ "$TOTAL_LINES" -gt "$MAX_LINES" ]; then
  echo ""
  echo "⚠️  WARNING: Your push contains ~${TOTAL_LINES} line changes (limit: ${MAX_LINES})."
  echo "   Consider splitting this into smaller PRs."
  echo ""
  echo "   To push anyway:  git push --no-verify"
  echo "   To cancel:       Ctrl+C"
  echo ""
  read -r -p "   Push anyway? [y/N]: " response
  if [[ ! "$response" =~ ^[Yy]$ ]]; then
    echo "Push cancelled."
    exit 1
  fi
fi

exit 0

2. .githooks/pre-push — Repo-specific hook for MSAL Common

#!/bin/bash
# ============================================================
# Pre-push hook — PR Size Soft Warning
# Repo: microsoft-authentication-library-common-for-objc
#
# Fires on every push to any remote branch.
# Bypass with: git push --no-verify
# ============================================================

EXTRA_EXCLUDES=(
  "^IdentityCore/tests/"
  "^IdentityCore/MSIDTestsHostApp/"
  "^scripts/"
)

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/pr-size-check.sh"

3. Makefile — Add setup target (create if not exists, or append if exists)

Check if a Makefile already exists in the repo root. If it does, append the setup target. If not, create it:

setup:
	git config core.hooksPath .githooks
	@echo "✅ Git hooks configured. Pre-push PR size check is now active."

.PHONY: setup

Important notes

• The hook fires on every push to any remote branch — not limited to dev
• It is a soft warning — developers can bypass with git push --no-verify
• pr-size-check.sh must be executable: chmod +x .githooks/pr-size-check.sh
• pre-push must be executable: chmod +x .githooks/pre-push
• Base branch for diff is always origin/dev (falling back to origin/main then origin/master)

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: do we have currently any pre push

Assistant: Let me check all 4 repos.

Assistant: Here is what exists across all 4 repos:

Repo	.githooks/ exists	pre-push	pre-commit
MSAL	❌ No .githooks/	❌ None	❌ None
MSAL Common	❌ No .githooks/	❌ None	❌ None
Broker	✅ Exists	❌ None	✅ Has one (clang-format check)
WorkplaceJoin	❌ No .githooks/	❌ None	❌ None

---

Key finding — Broker already has a pre-commit hook

#!/bin/sh

if git rev-parse --verify HEAD >/dev/null 2>&1
then
    against=HEAD
else
    against=$(git hash-object -t tree /dev/null)
fi

# Test clang-format
clangformatout=$(git clang-format -q)

exec 1>&2

if ...

</details>



<!-- START COPILOT CODING AGENT SUFFIX -->

*This pull request was created from Copilot chat.*
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[azure-pipelines]

This pull request does not update changelog.txt.

Please consider if this change would be noticeable to a partner or user and either update changelog.txt or resolve this conversation.

[Copilot]

Pull request overview

Adds a repo-local Git pre-push hook (enabled via core.hooksPath) to warn developers when a push is likely to result in an oversized PR, encouraging smaller/split PRs in this codebase.

Changes:

• Added reusable .githooks/pr-size-check.sh to compute changed-line “churn” vs a base branch with file-pattern exclusions.
• Added .githooks/pre-push entrypoint configuring repo-specific exclusions and sourcing the shared logic.
• Added a Makefile setup target to configure core.hooksPath = .githooks locally.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
Makefile	Adds make setup to enable local git hooks via core.hooksPath.
.githooks/pre-push	Hook entrypoint that sets repo-specific exclusions and sources shared logic.
.githooks/pr-size-check.sh	Implements base-branch selection, file filtering, line-change counting, and warning/prompt behavior.

[Copilot]

mapfile isn't available in the default /bin/bash on macOS (bash 3.2), so this hook will fail for many developers. Consider replacing this with a bash-3-compatible approach (e.g., a while IFS= read -r loop or using CHANGED_FILES=( $(...) ) with proper quoting) so the hook works on stock macOS shells.

Suggested change

	mapfile -t CHANGED_FILES < <(git diff --name-only "$BASE_BRANCH"...HEAD 2>/dev/null | grep -vE "$GREP_PATTERN")
	CHANGED_FILES=()
	while IFS= read -r changed_file; do
	CHANGED_FILES+=("$changed_file")
	done < <(git diff --name-only "$BASE_BRANCH"...HEAD 2>/dev/null | grep -vE "$GREP_PATTERN")

[Copilot]

The prompt uses read from stdin, but pre-push hooks receive the refs-to-push on stdin. If the size exceeds the limit, this read will consume the first ref line (not user input) and typically cancel the push unexpectedly. Read from /dev/tty (when available) or fall back to a non-interactive warning-only behavior when no TTY is present.

Suggested change

	read -r -p " Push anyway? [y/N]: " response
	if [[ ! "$response" =~ ^[Yy]$ ]]; then
	echo "Push cancelled."
	exit 1
	if [ -r /dev/tty ] && [ -w /dev/tty ]; then
	read -r -p " Push anyway? [y/N]: " response < /dev/tty
	if [[ ! "$response" =~ ^[Yy]$ ]]; then
	echo "Push cancelled."
	exit 1
	fi
	else
	echo "ℹ️ No interactive terminal available; continuing without confirmation."

[Copilot]

Base branch resolution is hardcoded to origin/*, but the pre-push hook is invoked with the target remote name as $1 and can be run against remotes other than origin. As written, pushes to a non-origin remote may incorrectly skip the check even if that remote has dev/main/master. Consider using the provided remote name (with a fallback to origin) when building refs/remotes/<remote>/... for the base branch candidates.

[Copilot]

This counts total diff hunk lines (additions + deletions), not “net line changes”. If the PR description intends net change, the counting logic needs to be adjusted; otherwise, update wording (e.g., “total line churn”) so the warning matches what’s being measured.