The queue: parking, the operator's order, blocked items (M2.2)

Several work items on the new loop (L1, D4):
- Switching parks the item on the workspace: its work is committed and its
  branch pushed; resuming checks the item's branch back out. Branches of
  open items are never set aside by a fresh workspace.
- Next item: the operator's "do #N next" first, otherwise the oldest.
- Issues with open Gitea dependencies are blocked until they close, checked
  at intake and on every round; status shows blocked items and the line.

Tests: queue unit tests, the property walk over several issues with
dependencies and a new parked_work_safe property (it catches parking
disabled), and an end-to-end test with two issues where B depends on A.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev/tests/test_loop_queue.py

@@ -0,0 +1,192 @@
+"""The queue in the new loop (M2.2): several items, parking and resuming on
+switch, the operator's order, and items blocked by Gitea dependencies (L1,
+D4). Real git on the throwaway build host; a fake Gitea."""
+
+from typing import Any
+
+from test_loop_milestones import DON, Forge, ScriptedModel, call, git, loop_agent
+from test_loop_milestones import world as world  # noqa: PLC0414 -- the fixture
+
+from nisse_dev.gitea import Comment, Issue
+from nisse_dev.loop.items import (
+    ANSWER,
+    BLOCKED,
+    GO_AHEAD,
+    MERGE,
+    READY,
+    WAITING,
+    item_for_issue,
+    loop_of,
+)
+from nisse_dev.transport import InboundMessage, InMemoryTransport
+
+
+def two_issues(forge: Forge) -> None:
+    forge.issues.append(Issue(15, "Add count_lines", "count lines", "don", ()))
+
+
+def item(world: dict[str, Any], issue: int) -> Any:
+    found = item_for_issue(world["store"], issue)
+    assert found is not None
+    return found
+
+
+def say(
+    transport: InMemoryTransport, world: dict[str, Any], issue: int, text: str
+) -> None:
+    transport.receive(DON, text, thread=loop_of(item(world, issue)).thread)
+
+
+def restated(transport: InMemoryTransport) -> list[str]:
+    """The threads restatements went up in, in order."""
+    return [m.thread for m in transport.outbound if m.text.startswith("rev-1:")]
+
+
+def test_switching_parks_the_work_and_resuming_finds_it(
+    world: dict[str, Any],
+) -> None:
+    forge: Forge = world["forge"]
+    two_issues(forge)
+    model = ScriptedModel(
+        [call("restate", text="count_words")],  # 14
+        [call("restate", text="count_lines")],  # 15
+        [  # 14, after its go: a PR
+            call("start_milestone", name="count_words"),
+            call("write_file", path="words.py", content="W = 1\n"),
+            call("finish_milestone", summary="count_words"),
+        ],
+        [  # 15, after its go: half done, then a question
+            call("start_milestone", name="count_lines"),
+            call("write_file", path="lines.py", content="L = 1\n"),
+            call("ask_human", question="one per line, or per paragraph?"),
+        ],
+        [  # 14, a review comment
+            call("write_file", path="words.py", content="W = 2\n"),
+            call("finish_milestone", summary="review fix"),
+        ],
+        [  # 15, answered: back where it was
+            call("run_command", command="cat lines.py"),
+            call("finish_milestone", summary="count_lines"),
+        ],
+    )
+    agent, transport = loop_agent(world, model)
+    agent.intake()
+    assert [loop_of(item(world, n)).wait for n in (14, 15)] == [GO_AHEAD, GO_AHEAD]
+    # The second item is acknowledged with its place in line.
+    assert any("#15" in m.text and "1 ahead" in m.text for m in transport.outbound)
+    say(transport, world, 14, "go")
+    assert loop_of(item(world, 14)).wait == MERGE
+    a_branch = loop_of(item(world, 14)).branch
+    say(transport, world, 15, "go")
+    assert loop_of(item(world, 15)).wait == ANSWER
+    # 15 was prepared while 14's branch was on the workspace: kept, not set aside.
+    assert not any("Set aside" in m.text for m in transport.outbound)
+    assert a_branch in world["repo"].local_branches()
+
+    [pr] = forge.prs
+    forge.comments[pr] = [Comment(7, "don", "make W 2", "t")]
+    agent.watch()
+    agent._schedule()
+
+    # Switching to 14 parked 15: its half-done work is committed and pushed.
+    b_branch = loop_of(item(world, 15)).branch
+    pushed = git(
+        "--git-dir", str(world["bare"]), "show", f"refs/heads/{b_branch}:lines.py"
+    )
+    assert pushed == "L = 1"
+    # 14's fix went to its own branch, without 15's work.
+    assert loop_of(item(world, 14)).wait == MERGE
+    files = git("--git-dir", str(world["bare"]), "ls-tree", "--name-only", a_branch)
+    assert "words.py" in files.split() and "lines.py" not in files.split()
+    assert "W = 2" in git(
+        "--git-dir", str(world["bare"]), "show", f"refs/heads/{a_branch}:words.py"
+    )
+
+    say(transport, world, 15, "one per line")
+    assert world["repo"].current_branch() == b_branch
+    assert (world["repo"].root / "lines.py").read_text() == "L = 1\n"
+    assert loop_of(item(world, 15)).wait == MERGE
+    assert len(forge.prs) == 2
+
+
+def test_a_blocked_item_waits_for_its_dependency_to_close(
+    world: dict[str, Any],
+) -> None:
+    forge: Forge = world["forge"]
+    two_issues(forge)
+    forge.deps[15] = [14]
+    model = ScriptedModel(
+        [call("restate", text="count_words")],
+        [call("restate", text="count_lines")],
+    )
+    agent, transport = loop_agent(world, model)
+    agent.intake()
+    assert item(world, 15).position == BLOCKED
+    assert loop_of(item(world, 15)).blocked_by == ("don/sandbox#14",)
+    assert any(
+        "#15" in m.text and "blocked by don/sandbox#14" in m.text
+        for m in transport.outbound
+    )
+    assert "#15 Add count_lines: blocked by don/sandbox#14" in agent.status()
+    # Talking to it doesn't start it.
+    say(transport, world, 15, "go")
+    assert item(world, 15).position == BLOCKED
+    assert "blocked" in transport.outbound[-1].text
+
+    forge.closed_issues.append(14)
+    agent.intake()
+    assert (item(world, 15).position, loop_of(item(world, 15)).wait) == (
+        WAITING,
+        GO_AHEAD,
+    )
+    assert loop_of(item(world, 15)).blocked_by == ()
+
+
+def test_an_item_that_gains_a_dependency_is_blocked(world: dict[str, Any]) -> None:
+    forge: Forge = world["forge"]
+    two_issues(forge)
+    model = ScriptedModel([call("restate", text="count_words")])
+    agent, _ = loop_agent(world, model)
+    agent._running = True  # hold the queue: both stay ready
+    agent.intake()
+    assert item(world, 15).position == READY
+    forge.deps[15] = [14]
+    agent.check_blocked()
+    assert item(world, 15).position == BLOCKED
+    agent._running = False
+    agent._schedule()  # 14 restates; 15 stays blocked
+    assert item(world, 15).position == BLOCKED
+    assert loop_of(item(world, 14)).wait == GO_AHEAD
+
+
+def test_the_operators_order_comes_before_the_oldest(world: dict[str, Any]) -> None:
+    forge: Forge = world["forge"]
+    two_issues(forge)
+    forge.issues.append(Issue(16, "Add count_chars", "count chars", "don", ()))
+    forge.issues.append(Issue(17, "Add count_vowels", "count vowels", "don", ()))
+    for n in (15, 16, 17):
+        forge.deps[n] = [14]
+    model = ScriptedModel(*[[call("restate", text=f"r{n}")] for n in range(4)])
+    agent, transport = loop_agent(world, model)
+    agent.intake()  # 14 runs; the rest wait on it
+    transport.receive(DON, "Do #17 next.")
+    assert "#17 goes first once it's unblocked" in transport.outbound[-1].text
+    transport.receive(DON, "do #99 next")
+    assert "#99 isn't one of my open work items" in transport.outbound[-1].text
+
+    forge.closed_issues.append(14)
+    agent.intake()
+    threads = {loop_of(item(world, n)).thread: n for n in (14, 15, 16, 17)}
+    assert [threads[t] for t in restated(transport)] == [14, 17, 15, 16]
+
+
+def test_status_shows_the_line(world: dict[str, Any]) -> None:
+    forge: Forge = world["forge"]
+    two_issues(forge)
+    agent, _ = loop_agent(world, ScriptedModel())
+    agent._running = True  # hold the queue
+    agent.intake()
+    assert "#14 Add count_words: ready, 1 of 2 in line" in agent.status()
+    assert "#15 Add count_lines: ready, 2 of 2 in line" in agent.status()
+    agent.handle(InboundMessage(DON, "do #15 next"), None)
+    assert "#15 Add count_lines: ready, 1 of 2 in line" in agent.status()