Repair unparseable publish workflow

[TorinKS]

What happened

publish-nuget.yaml has been invalid YAML since #6 merged. I introduced a PowerShell here-string in the exact-tag guard:

        run: |
          $tag = git describe --exact-match --tags HEAD 2>$null
          ...
            throw @"
HEAD is not at a tag, so the derived version would be wrong.

A here-string requires its body and closing "@ to begin at column 0. That un-indents straight out of the enclosing run: | block scalar:

YAMLException: can not read a block mapping entry;
a multiline key may not be an implicit key (121:13)

Why it went unnoticed

GitHub could not parse the file, so it could not apply the on: filters either. Every push produced a startup failure with zero jobs — including pushes to feature branches that tags: ['v*'] should have excluded. Six such runs accumulated.

None of them appeared in pull request checks, because this workflow is not a PR check. The PRs stayed green while the publisher was dead.

The consequence

v0.1.2 was tagged and its GitHub release published successfully — that is a different workflow. But nothing reached nuget.org:

https://api.nuget.org/v3-flatcontainer/windevicesnet/index.json
{"versions":["0.1.1"]}

Neither the tag push nor the new workflow_run trigger ever ran. The workflow_run mechanism from #8 is therefore still unproven; it has not had a chance to fire.

The fix

Build the message by concatenation so every line stays inside the block scalar. No behaviour change to the guard itself.

Verified with a YAML parser rather than by reading it:

File	Result
current main	YAMLException … (121:13)
this branch	parses; push, workflow_run and workflow_dispatch all intact

After merge

v0.1.2 already exists, so its tag-push event is spent. The publish will need one manual dispatch to catch up; the exact-tag guard will pass, since main sits on v0.1.2. The automatic path gets its first real test at v0.1.3.

Worth a follow-up: a workflow-lint check that runs as a PR check, so an unparseable workflow fails visibly instead of silently.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XnzCrAM46SttZnU6msznyN