[MendixMau]

Fixes #598

Direct lane

What changed and why:

bin/wire-company-brain.sh passed the multi-line pointer block to awk as -v blk="$block". BSD awk on macOS (20200816) refuses a newline in a -v value. As a result, every re-run (a moved brain, a changed block) left all surfaces untouched, yet still printed Updated: … rewritten in place and counted the surface.

What this PR changes:

• The block now reaches awk through the environment (ENVIRON["BLK"]), which is POSIX.
• The rewrite and append paths now print Updated only when awk && mv succeeded.
• On failure the script prints FAILED: …, leaves the file unchanged, and does not count the surface.

Impact

Row	Answer
Process	None. No gate reads this script and nothing new blocks. A failed surface now prints FAILED instead of a false Updated. The exit code is unchanged.
Dependencies	Only bin/wire-company-brain.sh and its fixture. No shared files, no new tools. ENVIRON works in BSD awk, gawk and mawk.
Context cost	None: no routed or always-loaded file touched.
Behaviour	n/a: script only.
Runtime	n/a.

Field evidence: reported in #598 from a scratch copy of a field-run project (three surfaces) on macOS 26 / BSD awk 20200816. The issue reproduces it on a clean master with an empty fixture. The issue's suggested ENVIRON change was tested there on BSD awk. This PR has not been run on macOS from here: the build container only has mawk.

Proof: the new section tests/wave2/test-company-brain.sh T2c uses a stub awk that enforces BSD's no-newline-in--v rule and otherwise runs the real awk. It also uses a stub that always fails, to check the reporting.

fixed (53c0560):                     PASS 50  FAIL 0
same fixture, 2ba8158's script:      PASS 46  FAIL 4
  FAIL re-point under BSD-awk rules left the old path: awk: newline in string
       Updated: CLAUDE.local.md — company brain block rewritten in place.
  FAIL failed rewrite still printed Updated
  FAIL no FAILED line
  FAIL count wrong: ... written to 1 instruction surface(s).

Master output under the stub matches the issue's report line for line. Only this fixture covers the script (grep -rl wire-company-brain tests/). bin/check-portability.sh is clean (335 files). The full suites were not run, per CLAUDE.md.

• No client data anywhere in the diff
• Size cap: 2 counted files, about 57 lines
• Test tier: T1 (fixture, failing on master). The field run is the reporter's macOS run in [bug] wire-company-brain.sh: re-run fails on macOS awk and still reports Updated #598.
• Instrument change: no parser, so no golden capture needed. Layout-independent (project root passed as an argument). macOS behaviour is emulated by the stub; Git Bash uses gawk, which accepts both forms.
• [n/a] New skill
• CHANGELOG.md line appended, crediting [bug] wire-company-brain.sh: re-run fails on macOS awk and still reports Updated #598
• [n/a] Bug entries

Review: pending independent review

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