Lab actions run with FORCE_COLOR=1, so their output can be colored

docs/protocol.md

@@ -288,7 +288,10 @@ steps = [["python", "demo.py", "--agent", "naive", "--model", "stable"]]
 ```
 
 Every step is an argv list. Steps run in order, and the first one that exits non-zero ends the
-action. Unknown keys are errors. Limits: 50 actions, 20 steps each, 100 arguments per step.
+action. Each step's output is followed by a line saying how it ended: `[done · 2.1 s]`,
+`[exit 3 · 0.4 s]`, `[stopped · 5.0 s]` or `[timed out · 1.0 s]`. Actions run with `FORCE_COLOR=1`
+and `CLICOLOR_FORCE=1` (unless already set), so output may contain ANSI color codes; a page showing it
+should render or strip them. Unknown keys are errors. Limits: 50 actions, 20 steps each, 100 arguments per step.
 
 ### Prepare a Lab
 

src/agent_runtime/labs.py

@@ -506,6 +506,11 @@ async def _execute(self, run: Run, lab: PreparedLab, action: Action) -> None:
         env["PATH"] = f"{lab.bin_dir}{os.pathsep}{env.get('PATH', '')}"
         env["VIRTUAL_ENV"] = str(lab.bin_dir.parent)
         env["PYTHONUNBUFFERED"] = "1"
+        # Output goes to a pipe, not a terminal, so programs would print no colors. The page that
+        # started the action renders ANSI colors, so ask for them (FORCE_COLOR and CLICOLOR_FORCE
+        # are the common conventions); a learner's NO_COLOR, if set, still wins in most tools.
+        env.setdefault("FORCE_COLOR", "1")
+        env.setdefault("CLICOLOR_FORCE", "1")
         deadline = time.monotonic() + action.timeout
         watchdog = asyncio.create_task(self._watch(run, deadline))
         try:

tests/test_labs.py

@@ -43,6 +43,13 @@
   "import time\\nfor i in range(400):\\n    print(i, flush=True)\\n    time.sleep(0.05)",
 ]]
 
+[actions.env]
+label = "Prints its color settings"
+steps = [[
+  "python", "-c",
+  "import os; print(os.environ.get('FORCE_COLOR'), os.environ.get('CLICOLOR_FORCE'))",
+]]
+
 [actions.hangs]
 label = "Times out"
 timeout = 1
@@ -141,7 +148,7 @@ class TestManifest:
     def test_valid(self):
         manifest = labs.parse_manifest(MANIFEST)
         assert manifest.lab_id == "demo-lab"
-        assert list(manifest.actions) == ["hello", "two", "slow", "hangs"]
+        assert list(manifest.actions) == ["hello", "two", "slow", "env", "hangs"]
         assert manifest.actions["two"].steps[1] == ("python", "-c", "import sys; sys.exit(3)")
         assert manifest.actions["hello"].timeout == labs.DEFAULT_TIMEOUT
         assert manifest.actions["hangs"].timeout == 1
@@ -213,7 +220,7 @@ class TestPrepare:
     def test_asks_once_per_lab_version(self, client, lab_repo):
         lab = _prepare(client, lab_repo)
         assert lab["lab_id"] == "demo-lab" and lab["commit"] == lab_repo[1]
-        assert [a["name"] for a in lab["actions"]] == ["hello", "two", "slow", "hangs"]
+        assert [a["name"] for a in lab["actions"]] == ["hello", "two", "slow", "env", "hangs"]
         assert len(client.prompts) == 1
         prompt = client.prompts[0]
         assert SITE in prompt and lab_repo[1] in prompt
@@ -279,6 +286,13 @@ def test_stop_and_one_run_at_a_time(self, client, lab_repo):
         assert re.search(r"\[stopped · \d+\.\d s\]\n$", stopped["output"])
         assert _start(client, lab, "hello").status_code == 200  # the lab is free again
 
+    def test_actions_are_asked_for_colors(self, client, lab_repo, monkeypatch):
+        monkeypatch.delenv("FORCE_COLOR", raising=False)
+        monkeypatch.delenv("CLICOLOR_FORCE", raising=False)
+        lab = _prepare(client, lab_repo)
+        done = _wait(client, _start(client, lab, "env").json()["run_id"])
+        assert "\n1 1\n" in done["output"], done["output"]
+
     def test_timeout(self, client, lab_repo):
         lab = _prepare(client, lab_repo)
         done = _wait(client, _start(client, lab, "hangs").json()["run_id"])