POST /workers?worktree=true returned HTTP 500 with a NullPointerException out
of ProcessBuilder.start(): acquireWithWorktree resolved the repo root from
firstNonBlank(requestedCwd, callerCwd), and a plain REST spawn supplies
neither (BridgedApp hardcodes callerCwd=null, "no MCP caller over REST"). Both
null yielded null, putting `git -C null rev-parse --show-toplevel` on the
command line.
Now resolved through launcher.effectiveCwd, the CB-112 chain used everywhere
else (requested -> profile cwd -> caller -> daemon cwd -> "."), which is
documented never to return null. The non-worktree path in this same class
already went through it; only the worktree branch was missed.
Also fixes a second latent bug in the same line: firstNonBlank never consulted
the profile's configured cwd:, so a worktree spawn silently ignored a pinned
per-profile working directory. effectiveCwd honours it.
Removes firstNonBlank, now dead (this was its only call site) — javac ignores
an unused private method but IDE inspections flag it, and CLAUDE.md requires a
clean bill.
Why 311 tests missed it: the null/null case only arises over REST, and
WorktreeSessionManagerTest always passes an explicit cwd. Over MCP callerCwd is
populated from the caller PID, so the feature worked there. This is the third
REST-vs-MCP divergence found this month, after CB-505's path-trusted session id.
The one-line change was implemented by an opencode-free worker over the bridge
in an isolated worktree (branch worker/cb-507-worktree-cwd-npe-3e9c3b-3); the
dead-helper cleanup and the explanatory comment were added on integration.
A regression test is still outstanding and is being delegated separately.
kevin
6804676a96