The whole-prompt scan for "Current working directory:" matched USER project
content, not just Hermes' own host-info line. The prompt embeds AGENTS.md /
CLAUDE.md / .cursorrules in the context tier, which sits AFTER the host-info
block, and line_value() takes the LAST match — so any project file containing
a line starting with that label won the scan.
The comparison then ran runtime state against project prose, a mismatch that
never clears: the stored prompt was rejected on EVERY turn, rebuilding the
system prompt each message and destroying the prefix cache for the whole
session. Strictly worse than the staleness the check exists to catch, and
invisible to CI because no test encoded the invariant.
"last match wins" was only ever safe because Model/Provider/Platform live in
the volatile tier at the very END of the prompt. The cwd line is the one field
read from the STABLE tier near the start, so it needs an anchored read:
locate Hermes' own "User home directory:" line and take the working-directory
line that follows it.
Verified against the real builder on a real AIAgent, not a stub:
- stable cwd, clean project -> prompt REUSED (0 rebuilds)
- stable cwd, AGENTS.md naming the
field -> prompt REUSED (was: rebuild/turn)
- drifted cwd -> rebuilt
- drifted cwd, AGENTS.md naming the
NEW cwd -> rebuilt (prose can't mask drift)
Also re-verified no spurious rebuild across all five cwd-resolution paths
(pinned contextvar, TERMINAL_CWD, launch dir, symlinked workspace,
trailing-slash cwd).
The contributor's fixtures omitted the host-info anchor, so they silently
stopped exercising the cwd path once the read was anchored; reshaped them to
match real prompt structure via a _host_block() helper.
