fix(unic-archon-dlc): /build pushes a branch that lacks a source file commit-session left out #667

What happens

In /build, after #439 (PR #665), commit-session (a prompt node) stages and commits, and push-branch (a bash node) pushes. Before the push, push-branch checks that the five Session artefacts are at HEAD and match the working tree. It does not check the source and test files the build loop wrote.

So if commit-session leaves a source or test file out of the commit, the push succeeds, the branch lacks the file, and the run goes on. On pass, open-pr opens a pull request without it. On any other verdict, the cancel: message points the operator at a branch that lacks it. The only trace is git status --porcelain, which push-branch prints to stderr.

One prompt node at 579b4ef4 had the same gap, so #439 did not widen it. Criterion 6 of #439, amended 2026-10-28, names it as an open question and points here.

Not decided

• Whether push-branch should fail on any uncommitted change outside a named set of scratch paths, or whether that list belongs in one place that both nodes read.
• Whether the gap matters in practice: the build loop commits in its RED and GREEN phases, so commit-session may rarely have source or test files left to stage. Nobody has measured this.

Found while the maintainer accepted the two-node shape of PR #665. Parent map: #498.