Add agents.md - #6709

[taskcluster 2026-08-24T22:37:57.901Z] Worker Type (proj-bugbug/batch) settings:
[taskcluster 2026-08-24T22:37:57.901Z]   {
[taskcluster 2026-08-24T22:37:57.901Z]     "generic-worker": {
[taskcluster 2026-08-24T22:37:57.901Z]       "config": {
[taskcluster 2026-08-24T22:37:57.901Z]         "headlessTasks": false
[taskcluster 2026-08-24T22:37:57.901Z]       },
[taskcluster 2026-08-24T22:37:57.901Z]       "engine": "multiuser",
[taskcluster 2026-08-24T22:37:57.901Z]       "go-arch": "amd64",
[taskcluster 2026-08-24T22:37:57.901Z]       "go-os": "linux",
[taskcluster 2026-08-24T22:37:57.901Z]       "go-version": "go1.26.2",
[taskcluster 2026-08-24T22:37:57.901Z]       "release": "https://github.com/taskcluster/taskcluster/releases/tag/v99.1.0",
[taskcluster 2026-08-24T22:37:57.901Z]       "revision": "c76d61efe4bdc1a05bcec848739cd41ebf061f01",
[taskcluster 2026-08-24T22:37:57.901Z]       "source": "https://github.com/taskcluster/taskcluster/commits/c76d61efe4bdc1a05bcec848739cd41ebf061f01",
[taskcluster 2026-08-24T22:37:57.901Z]       "version": "99.1.0"
[taskcluster 2026-08-24T22:37:57.901Z]     },
[taskcluster 2026-08-24T22:37:57.901Z]     "image": "projects/community-tc-workers/global/images/generic-worker-ubuntu-24-04-aaynirqnxlbwcojgnbeo",
[taskcluster 2026-08-24T22:37:57.901Z]     "instance-id": "7664598713031031248",
[taskcluster 2026-08-24T22:37:57.901Z]     "instance-type": "projects/757942385826/machineTypes/n2-standard-2",
[taskcluster 2026-08-24T22:37:57.901Z]     "local-ipv4": "10.142.0.4",
[taskcluster 2026-08-24T22:37:57.901Z]     "machine-setup": {

...(61 lines hidden)...

[INFO] Initializing environment for https://github.com/pre-commit/mirrors-prettier.
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-prettier:prettier@3.1.0.
[INFO] Initializing environment for https://github.com/astral-sh/ruff-pre-commit.
[INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Initializing environment for https://github.com/codespell-project/codespell.
[INFO] Initializing environment for https://github.com/marco-c/taskcluster_yml_validator.
[INFO] Initializing environment for https://github.com/asottile/yesqa.
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-mypy.
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-mypy:types-pkg_resources==0.1.2,types-python-dateutil==2.9.0.20260716,types-PyYAML==6.0.12.20260724,types-orjson==3.6.2,types-tabulate==0.10.0.20260508,types-requests==2.33.0.20260712.
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-mypy:types-pkg_resources==0.1.2,types-requests==2.33.0.20260712,types-Flask==1.1.6,types-redis==4.6.0.20241004,types-python-dateutil==2.9.0.20260716,types-orjson==3.6.2,types-tabulate==0.10.0.20260508.
[INFO] Installing environment for https://github.com/pre-commit/mirrors-prettier.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/astral-sh/ruff-pre-commit.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/codespell-project/codespell.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/marco-c/taskcluster_yml_validator.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/asottile/yesqa.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/pre-commit/mirrors-mypy.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/pre-commit/mirrors-mypy.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
prettier.................................................................Passed
ruff check...............................................................Passed
ruff format..............................................................Passed
check python ast.........................................................Passed
check docstring is first.................................................Passed
check that executables have shebangs.....................................Passed
check for merge conflicts................................................Passed
check for broken symlinks................................................Passed
debug statements (python)................................................Passed
trim trailing whitespace.................................................Passed
check yaml...............................................................Passed
mixed line ending........................................................Passed
python tests naming......................................................Passed
check json...............................................................Passed
check vcs permalinks.....................................................Passed
codespell................................................................Passed
taskcluster_yml..........................................................Passed
Strip unnecessary `# noqa`s..............................................Passed
mypy-bugbug..............................................................Passed
mypy-bugbug-http.........................................................Passed
Check for useless excludes...............................................Passed
[taskcluster 2026-08-24T22:40:27.025Z]                        Exit Code: 0
[taskcluster 2026-08-24T22:40:27.025Z]                        User Time: 32.78ms
[taskcluster 2026-08-24T22:40:27.025Z]                      Kernel Time: 37.302ms
[taskcluster 2026-08-24T22:40:27.025Z]                        Wall Time: 2m5.077812617s
[taskcluster 2026-08-24T22:40:27.025Z]  Average Available System Memory: 6.29 GiB
[taskcluster 2026-08-24T22:40:27.025Z]       Average System Memory Used: 1.46 GiB
[taskcluster 2026-08-24T22:40:27.025Z]          Peak System Memory Used: 1.74 GiB
[taskcluster 2026-08-24T22:40:27.025Z]              Total System Memory: 7.75 GiB
[taskcluster 2026-08-24T22:40:27.025Z]                           Result: SUCCEEDED
[taskcluster 2026-08-24T22:40:27.025Z] === Task Finished ===
[taskcluster 2026-08-24T22:40:27.025Z] Task Duration: 2m5.07838777s