`run_diff_plan`'s `next_step` read the module-level `state.root` each
time it started a step, so a multi-step plan could change repositories
halfway through.
An unborn `AM`/`AD` row produces a TWO-STEP plan --- staged patch, then
unstaged patch --- and the second step is spawned from the first one's
completion callback. `state.root` is reassigned by `_deliver_root`,
which runs whenever a concurrent `git.status` for another repository
finishes resolving its worktree. Start a diff in A, run `git.status` in
B before the first patch lands, and the plan's second step runs with B
as its cwd and A's path: git there matches nothing, so the unstaged half
silently renders "(no changes)" instead of the worktree delta it exists
to show.
The root is now captured at the keypress and threaded through the plan
as a parameter; `state.root` is not read inside the plan at all. Same
shape as the generation counter fixed in `ffe5ae2` --- capture at the
INVOCATION, never at the continuation --- and the third instance of it,
`state.branch`, is already read at the keypress on the same line.
Witnessed by `g6_22`: an unborn `AM` row's two-step plan with
`state.root` reassigned between the keypress and the first step's
completion, asserting BOTH spawned diff argvs carry the originally
captured root and neither carries the other repository's. Driven through
`_deliver_root` because no arrangement of real subprocess timing can
guarantee the interleaving, and nothing is pumped between the keypress
and the reassignment, so step 1 is genuinely in flight.
The argv assertion is the load-bearing half. A test that checked only
the first step, or only that a diff rendered, passes on the broken code:
step 1 is spawned synchronously from the keypress, and step 2 against
the wrong repository exits 0 with empty output rather than failing.
Mutation-verified --- restoring the `state.root` read fails the test on
the second argv.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
3eca5e8f60