plans: Claude pin default-path tests brief from row 72 review (N1)

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/plans/2026-10-11_claude-pin-and-coder-grant.md

@@ -112,3 +112,48 @@ Who may reassign doesn't change; only the grant that never worked goes.
 Dewey approves on the row's issue naming the candidate manifest. The
 tasks, bus, business and harness node suites and every `scripts/test-*.sh` green
 on Sage's gate rerun.
+
+## Claude pin default-path tests
+
+Added by Sage, lead, on 2026-10-11 from Filbert's row 72 note N1
+(comment 27460 on #1566).
+
+### Problem
+
+Row 72 tests a pin given with `--claude` and a pin set by hand in the
+adapter. When `bus-service.sh` takes the default from `command -v claude`,
+the value goes through the same absolute-path, character, `-f` and `-x`
+checks, but no test sends a default down that path. Two real cases are
+untested. In the first, the only `claude` on `PATH` is a file without the
+execute bit. In the second, the `PATH` directory holding `claude` has a
+space in its name, and systemd would split the pin at the space. The code
+refuses both today; Filbert checked by hand.
+
+### Owner and reviewer
+
+Owner: Rocko, after row 73. Reviewer: Filbert. Rocko has no Gitea token;
+Sage runs the review request as jarvis.
+
+### Files owned
+
+- `packages/cli/tests/host.test.mjs`
+- `agents/rocko/work/queue-<row>/`
+
+### What ships
+
+- A default test where the only `claude` on `PATH` is a regular file
+  without the execute bit: render refuses and prints nothing on stdout.
+- A default test where `claude` sits in a `PATH` directory whose name has
+  a space: render refuses and prints nothing on stdout.
+- The packet names a mutant for each check that the new tests kill and
+  shows that each survives on the base.
+
+### Out of scope
+
+Any change to `scripts/bus-service.sh` or `adapters/claude/adapter.sh`.
+If a test shows the code doesn't refuse, stop and tell Sage.
+
+### Gate
+
+Filbert approves on the row's issue naming the candidate manifest. The cli
+node suite and every `scripts/test-*.sh` green on Sage's gate rerun.