name: Detect changed files

# Outputs the list of files changed in a PR, one per line, wrapped

# with ^ and $ anchors (e.g. ^ui/src/App.tsx$). Jobs match with

# contains() using anchors for precise substring matching:

# '^scripts/' — full tree under a root directory

# '.go$' — file extension (won't match .gotmpl)

# '^go.mod$' — exact root file

#

# Empty output (push events, API failure, 3000+ files) is falsy,

# so jobs prefix with: !needs.detect-changes.outputs.files ||

# to default to "run" when the file list is unavailable.

#

# Optional run_all input: patterns that affect all jobs. If any

# changed file matches, output stays empty so all jobs run.

on:

workflow_call:

inputs:

run_all:

description: >

Newline-separated list of patterns (same ^/$ anchored

format as the output). If any changed file matches any

of these, output is empty and all jobs run.

type: string

required: false

default: ''

outputs:

files:

description: >

Newline-separated list of changed filenames, or empty

string on push/failure (falsy, so jobs default to run).

value: ${{ jobs.detect.outputs.files }}

ui_only:

description: >

'true' when every changed file is under ui/, empty

otherwise. Skip non-UI jobs with: if: !needs.X.outputs.ui_only

value: ${{ jobs.detect.outputs.ui_only }}

jobs:

detect:

runs-on: ubuntu-latest

outputs:

files: ${{ steps.list.outputs.files }}

ui_only: ${{ steps.list.outputs.ui_only }}

steps:

- name: List changed files

id: list

env:

GH_TOKEN: ${{ github.token }}

GH_REPO: ${{ github.repository }}

PR_NUMBER: ${{ github.event.pull_request.number }}

RUN_ALL: ${{ inputs.run_all }}

WORKFLOW_FILE_PATH: ".github/workflows/detect-changes.yml"

shell: bash

run: |

set -eo pipefail

if [[ -z "${PR_NUMBER}" ]]; then

echo "Not a PR" >&2

exit 0

fi

if ! output="$(gh api "repos/${GH_REPO}/pulls/${PR_NUMBER}/files" --paginate --jq '.[].filename')"; then

echo "::warning::GitHub API call failed" >&2

exit 0

fi

mapfile -t files < <(echo -n "${output}")

echo "Changed files (${#files[@]}):" >&2

printf ' %s\n' "${files[@]}" >&2

if [[ ${#files[@]} -ge 3000 ]]; then

echo "::warning::PR has 3000+ changed files" >&2

exit 0

fi

anchored=$(printf '^%s$\n' "${files[@]}")

if echo "${anchored}" | grep -qF "^${WORKFLOW_FILE_PATH}$"; then

echo "detect-changes.yml modified, running all jobs" >&2

exit 0

fi

if [[ -n "${RUN_ALL}" ]]; then

while IFS= read -r pattern; do

[[ -z "$pattern" ]] && continue

if echo "${anchored}" | grep -qF "$pattern"; then

echo "run_all: matched '${pattern}', running all jobs" >&2

exit 0

fi

done <<< "${RUN_ALL}"

fi

if [[ ${#files[@]} -gt 0 ]]; then

{

echo "files<<EOF"

printf '^%s$\n' "${files[@]}"

echo "EOF"

} >> "${GITHUB_OUTPUT}"

if ! echo "${anchored}" | grep -qv '^\^ui/'; then

echo "All changed files are under ui/" >&2

echo "ui_only=true" >> "${GITHUB_OUTPUT}"

fi

fi