Fix macOS CI `skipif` condition

The Darwin-only debugger skip in `49fc92b0` passed the raw
`CI=true` env string to `skipif`, so `pytest` evaluated `true`
as Python source and failed at setup instead of skipping the
issue #320 node.

Cast `_ci_env` through `bool()` so the marker always receives
a boolean while retaining Linux coverage.

Prompt-IO: ai/prompt-io/opencode/20260820T135125Z_9f99043b_prompt_io.md

(this patch was generated in some part by `opencode` using
`gpt-5.6-sol` (`openai`))

ai/prompt-io/opencode/20260820T135125Z_9f99043b_prompt_io.md

@@ -0,0 +1,35 @@
+---
+model: openai/gpt-5.6-sol
+service: opencode
+session: 76c5d31c-5a2f-4503-9b16-410ee7f4fab3
+timestamp: 2026-08-20T13:51:25Z
+git_ref: 9f99043b
+scope: tests
+substantive: true
+raw_file: 20260820T135125Z_9f99043b_prompt_io.raw.md
+---
+
+## Prompt
+
+Continue preparing PR #481 for landing after the prior test and
+documentation commits were pushed. Follow CI and proceed with clear next
+steps without merging or changing remote content unasked.
+
+## Response summary
+
+Followed CI through completion and found both macOS jobs failed because the
+new `skipif` expression returned the `CI=true` environment string. Corrected
+the condition to pass pytest a boolean before evaluating the marker. A
+simulated Darwin-CI run now skips cleanly, and the sequential TCP and UDS
+debugger/tooling suites each pass with 39 passed and 6 skipped.
+
+## Files changed
+
+- `tests/devx/test_debugger.py` - coerce the Darwin-CI skip condition to a
+  boolean.
+
+## Human edits
+
+The human pushed the preceding commits, directed the agent to continue, and
+approved recording this test-only follow-up in Prompt-IO. No direct
+source-line edits were made by the human.

ai/prompt-io/opencode/20260820T135125Z_9f99043b_prompt_io.raw.md

@@ -0,0 +1,22 @@
+---
+model: openai/gpt-5.6-sol
+service: opencode
+timestamp: 2026-08-20T13:51:25Z
+git_ref: 9f99043b
+diff_cmd: git diff HEAD~1..HEAD
+---
+
+Continue preparing PR #481 for landing after the test and documentation
+commits were pushed. Follow the new CI run to completion and diagnose any
+failures.
+
+> `git diff HEAD~1..HEAD -- tests/devx/test_debugger.py`
+
+Both macOS jobs failed while evaluating the new `skipif` marker. The
+expression returned the `CI=true` environment string instead of a boolean,
+so pytest evaluated `true` as Python source and raised `NameError` during
+test setup. Coerce `_ci_env` to `bool` so pytest receives a boolean marker
+condition on Darwin CI.
+
+Verification should exercise the condition with `CI=true` and a simulated
+Darwin platform, then rerun the debugger/tooling TCP and UDS suites.

tests/devx/test_debugger.py

@@ -772,7 +772,7 @@ def test_multi_subactors_root_errors(
 @pytest.mark.skipif(
     platform.system() == 'Darwin'
     and
-    _ci_env,
+    bool(_ci_env),
     reason=(
         'Nested crash-REPL ordering is unreliable on macOS CI; '
         'see https://github.com/goodboy/tractor/issues/320'