Three consecutive orders shipped a backend-correct field that never
reached a screen, all on a green suite: gradeBands (required by no
serving code), served_grade (dropped at the adapter boundary),
GradeScaleLegend (imported by nothing). Each was caught by luck on a later
re-check, and in two of the three I had already reported the wiring done.
WHY GREEN TESTS COULD NOT SEE IT: backend tests stop at the API payload.
They prove a field is PRODUCED and say nothing about whether it is
CONSUMED. Invisible by construction, not an oversight in any one test.
THE TRAP, NAMED: the difficulty pools in the backend, so by the time a
field exists on the payload it feels finished. What remains is a
three-line adapter change nobody considers worth verifying, so it gets
claimed rather than traced. The last inch is the one with no friction,
which is exactly why it gets skipped. "I added the field" and "a user can
see it" are different claims and only the first is fun.
THE GUARD traces each promised field the whole way: payload -> adapter
consumes -> component renders -> component is MOUNTED. Mounted is
transitive to a Next entry point (page/layout/template), the only thing
that puts a pixel on screen, depth-limited so an import cycle cannot hang
the suite.
Container rows are exempted EXPLICITLY, not silently: served_grade carries
container:true plus a rendersVia list, and a separate assertion checks
every named part actually renders. The exemption is auditable and cannot
hide an unrendered field.
The guard tests itself -- an orphan component must report unmounted, and
the contract must be non-empty, since an empty contract passing vacuously
is how this would most plausibly rot.
RETRO-PROOF: run unchanged against 3591c76, before the wiring, it goes
11 failed / 8 passed and names the exact bugs -- "the ceiling stance /
grade scale legend - its component is MOUNTED, not merely written", "the
served grade object - the adapter consumes it", "whether the band
separates from the baseline - a component actually renders it". Green on
the current tree.
HONEST SCOPE LIMIT: gradeBands is NOT in the contract and would not be
caught. It is a backend module, not a promised user-facing field, and it
is correctly unwired -- every band collapses to base-rate at current
resolution. Out of scope by design, not oversight.
Now in the standing suite, so the three-gate floor is tests green
(including reachability) + build exit 0 + fingerprint. No serving or model
change. p_win never mutated. No Bonferroni slot.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W1sivYNqY2TS5ftykmHBU9
