diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 42df6bc..2efe478 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -55,6 +55,19 @@ repos:
         entry: bash -lc 'go vet ./...'
         language: system
         pass_filenames: false
+      - id: require-issue-reference
+        name: issue reference check (warning)
+        description: Warn if commit message lacks a GitHub issue reference like #123
+        entry: bash -lc 'scripts/require_issue_ref.sh "$1"'
+        language: system
+        stages: [commit-msg]
+        pass_filenames: true
+      - id: line-count-limit
+        name: line count limit (warn >500, block >750)
+        description: Warn on files 501–750 lines; fail if any >750 lines
+        entry: bash -lc 'scripts/line_count_check.sh'
+        language: system
+        pass_filenames: true
 
   # GolangCI-Lint (static analysis)
   - repo: https://github.com/golangci/golangci-lint
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index fb4745d..1fc582b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -67,6 +67,10 @@ Our pre-commit `no-commit-to-branch` hook blocks commits on non-conforming branc
   ```
   or commit normally and the `commit-msg` hook will validate.
 
+- Issue reference: include a GitHub issue reference (`#<issue>`) somewhere in the commit
+  message (body or footer). Examples: `Refs #29`, `Closes #102`.
+  The commit-msg hook only warns if missing; commits still proceed.
+
 ## Development Workflow
 
 - Create or pick up an issue. For new features, propose design via an issue first.
@@ -86,6 +90,13 @@ Our pre-commit `no-commit-to-branch` hook blocks commits on non-conforming branc
 - `go fmt ./...` and `go vet ./...` run via pre-commit.
 - `golangci-lint` runs as part of pre-commit; CI integration may run it on PRs as well.
 
+## File Size Guidelines
+
+- Keep source files concise. The pre-commit hook warns when a changed file exceeds 500 lines and blocks commits for files over 750 lines.
+  - Warning: 501–750 lines (message only; commit proceeds)
+  - Error: >750 lines (commit blocked)
+  - Consider splitting large files into smaller units for readability and maintainability.
+
 ## Security & Secrets
 
 - `detect-secrets` scans for potential credentials.
diff --git a/scripts/line_count_check.sh b/scripts/line_count_check.sh
new file mode 100644
index 0000000..a868114
--- /dev/null
+++ b/scripts/line_count_check.sh
@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Pre-commit hook: Warn for files >500 lines (up to 750),
+# block commit if any file exceeds 750 lines.
+
+warn_threshold=500
+block_threshold=750
+
+warned=0
+blocked=0
+declare -a blocked_files
+declare -a warned_files
+
+is_regular_file() {
+  [[ -f "$1" ]]
+}
+
+line_count() {
+  # Use wc -l; handle files with no trailing newline
+  wc -l < "$1" | awk '{print $1}'
+}
+
+for f in "$@"; do
+  # Skip if not a regular file (deleted, dir, symlink, etc.)
+  if ! is_regular_file "$f"; then
+    continue
+  fi
+
+  # Skip binary files: if grep treating binary as non-text, skip
+  if ! LC_ALL=C grep -Iq . "$f"; then
+    continue
+  fi
+
+  cnt=$(line_count "$f" || echo 0)
+
+  if (( cnt > block_threshold )); then
+    blocked=1
+    blocked_files+=("$f ($cnt lines)")
+  elif (( cnt > warn_threshold )); then
+    warned=1
+    warned_files+=("$f ($cnt lines)")
+  fi
+done
+
+if (( warned == 1 )); then
+  echo "[line-count] Warning: some files exceed ${warn_threshold} lines:" >&2
+  for w in "${warned_files[@]}"; do
+    echo "  - $w" >&2
+  done
+fi
+
+if (( blocked == 1 )); then
+  echo "[line-count] Error: files exceed ${block_threshold} lines; reduce size or split files:" >&2
+  for b in "${blocked_files[@]}"; do
+    echo "  - $b" >&2
+  done
+  exit 1
+fi
+
+exit 0
diff --git a/scripts/require_issue_ref.sh b/scripts/require_issue_ref.sh
new file mode 100644
index 0000000..0259b6c
--- /dev/null
+++ b/scripts/require_issue_ref.sh
@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# pre-commit commit-msg hook: check commit message references a GitHub issue
+# Usage: scripts/require_issue_ref.sh <commit_msg_file>
+
+msg_file="${1:-}"
+if [[ -z "${msg_file}" || ! -f "${msg_file}" ]]; then
+  echo "commit-msg hook error: commit message file not found" >&2
+  exit 1
+fi
+
+# Read first line (subject)
+subject="$(head -n1 "$msg_file" | tr -d '\r')"
+lower_subject="$(printf '%s' "$subject" | tr '[:upper:]' '[:lower:]')"
+
+# Allow merges and reverts to pass without extra checks
+if [[ "$lower_subject" =~ ^merge\  || "$lower_subject" =~ ^revert\  ]]; then
+  exit 0
+fi
+
+# Allow automated release/version bump commits
+if [[ "$lower_subject" =~ ^chore\(release\):\  || "$lower_subject" =~ ^bump: ]]; then
+  exit 0
+fi
+
+# Require a #<num> anywhere in the message (subject or body)
+if rg -N --pcre2 -q "#[0-9]{1,7}\b" "$msg_file" 2>/dev/null; then
+  exit 0
+fi
+
+# Fallback to grep if ripgrep is unavailable
+if command -v grep >/dev/null 2>&1 && grep -Eq "#[0-9]{1,7}(\b|$)" "$msg_file"; then
+  exit 0
+fi
+
+echo "[issue-ref] Warning: no GitHub issue reference found (e.g., 'refs #123' or 'closes #123')." >&2
+echo "Include '#<num>' in the message body or footer when possible." >&2
+exit 0