diff --git a/.zshrc b/.zshrc
index 0dd2f1e..91cb836 100644
--- a/.zshrc
+++ b/.zshrc
@@ -89,12 +89,11 @@ alias rebase="bash ~/development-configuration/scripts/rebase_and_push.sh"
 alias main="bash ~/development-configuration/scripts/checkout_main_and_pull.sh"
 alias master="bash ~/development-configuration/scripts/checkout_master_and_pull.sh"
 alias fetch-all="bash ~/development-configuration/scripts/fetch_all.sh"
+alias squash_by_day="bash ~/development-configuration/scripts/squash_by_day.sh"
 
 # Added by LM Studio CLI (lms)
 export PATH="$PATH:/Users/jackplowman/.lmstudio/bin"
 # End of LM Studio CLI section
 
-
-
 # Added by Antigravity CLI installer
 export PATH="/Users/jackplowman/.local/bin:$PATH"
diff --git a/development-configuration/scripts/squash_by_day.sh b/development-configuration/scripts/squash_by_day.sh
new file mode 100644
index 0000000..02b137e
--- /dev/null
+++ b/development-configuration/scripts/squash_by_day.sh
@@ -0,0 +1,116 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat <<'EOF'
+Usage: squash-commits-by-day.sh [BASE]
+
+Rebase the current branch onto BASE, then combine its commits by author date.
+Each resulting commit is named "Squash for YYYY-MM-DD".
+
+When BASE is omitted, the script tries origin/HEAD, main, then master.
+
+The selected history must be linear and the worktree must be clean.
+This command rewrites Git history and does not create a backup branch.
+EOF
+}
+
+die() {
+  printf 'Error: %s\n' "$*" >&2
+  exit 1
+}
+
+if [[ ${1:-} == "-h" || ${1:-} == "--help" ]]; then
+  usage
+  exit 0
+fi
+
+(( $# <= 1 )) || die "expected at most one BASE argument"
+git rev-parse --git-dir >/dev/null 2>&1 || die "not inside a Git repository"
+git symbolic-ref -q HEAD >/dev/null || die "HEAD must be attached to a branch"
+[[ -z $(git status --porcelain) ]] || die "worktree and index must be clean"
+
+branch=$(git symbolic-ref --short HEAD)
+
+if [[ $# == 1 ]]; then
+  base_ref=$1
+else
+  base_ref=""
+  remote_default=$(git symbolic-ref -q --short refs/remotes/origin/HEAD || true)
+  for candidate in "$remote_default" main master; do
+    if [[ -n $candidate ]] && git rev-parse --verify "$candidate^{commit}" >/dev/null 2>&1; then
+      base_ref=$candidate
+      break
+    fi
+  done
+  [[ -n $base_ref ]] || die "could not detect a default branch; pass BASE explicitly"
+fi
+
+base=$(git rev-parse --verify "$base_ref^{commit}") || die "invalid BASE: $base_ref"
+[[ $base != $(git rev-parse HEAD) ]] || die "current branch is already at BASE ($base_ref)"
+
+printf 'Rebasing %s onto %s...\n' "$branch" "$base_ref"
+if ! git rebase "$base_ref"; then
+  die "rebase stopped; resolve conflicts and run 'git rebase --continue' or abort it"
+fi
+
+base=$(git rev-parse --verify "$base_ref^{commit}")
+old_head=$(git rev-parse HEAD)
+revision_range="$base..HEAD"
+
+commits=()
+while IFS= read -r commit; do
+  commits+=("$commit")
+done < <(git rev-list --reverse --topo-order "$revision_range")
+
+(( ${#commits[@]} > 0 )) || die "no commits to rewrite"
+
+for commit in "${commits[@]}"; do
+  parents=$(git rev-list --parents -n 1 "$commit")
+  [[ $(wc -w <<<"$parents" | tr -d ' ') -le 2 ]] || \
+    die "selected history contains merge commit $commit"
+done
+
+new_parent=$base
+group_date=""
+group_last=""
+
+create_group_commit() {
+  local commit=$1 day=$2 tree author_name author_email author_date new_commit
+  tree=$(git rev-parse "$commit^{tree}")
+  author_name=$(git show -s --format=%an "$commit")
+  author_email=$(git show -s --format=%ae "$commit")
+  author_date=$(git show -s --format=%aI "$commit")
+
+  if [[ -n $new_parent ]]; then
+    new_commit=$(printf 'Squash for %s\n' "$day" | \
+      GIT_AUTHOR_NAME="$author_name" GIT_AUTHOR_EMAIL="$author_email" \
+      GIT_AUTHOR_DATE="$author_date" GIT_COMMITTER_DATE="$author_date" \
+      git commit-tree "$tree" -p "$new_parent")
+  else
+    new_commit=$(printf 'Squash for %s\n' "$day" | \
+      GIT_AUTHOR_NAME="$author_name" GIT_AUTHOR_EMAIL="$author_email" \
+      GIT_AUTHOR_DATE="$author_date" GIT_COMMITTER_DATE="$author_date" \
+      git commit-tree "$tree")
+  fi
+  new_parent=$new_commit
+}
+
+for commit in "${commits[@]}"; do
+  commit_date=$(git show -s --format=%aI "$commit")
+  commit_date=${commit_date:0:10}
+
+  if [[ -n $group_date && $commit_date != "$group_date" ]]; then
+    create_group_commit "$group_last" "$group_date"
+  fi
+  group_date=$commit_date
+  group_last=$commit
+done
+create_group_commit "$group_last" "$group_date"
+
+git update-ref "refs/heads/$branch" "$new_parent" "$old_head"
+git reset --hard "$new_parent" >/dev/null
+
+printf 'Rebased and rewrote %s onto %s.\n' "$branch" "$base_ref"
+git log --oneline --decorate --date=short --format='%h %ad %s' \
+  ${base:+"$base.."}HEAD