Live probing against Penpot 2.16.2 (repeated, on a dedicated scratch page,
cleaned up afterwards) shows board.flex.appendChild(shape) is a real
function, distinct from board.appendChild, arity 1, throws nothing, and
preserves visual insertion order -- unlike board.appendChild, which still
inserts at the front as documented. The prior "broken" claim traces to the
MCP server's own high_level_overview() text (CRITICAL / BROKEN / NEVER use),
never verified with a live throw, and possibly confused with a real doc bug
that mislabels the grid 3-arg example as board.flex.
Removes flex.appendChild from the lint's FORBIDDEN patterns and from the
gate 5 forbidden-behavior veto, updates PENPOT_API_VERIFIED.md with the
verified facts, and drops the now-obsolete pattern from the replay filters
in 05_build_dataset.py and 07_build_lora2_mix.py.
The 41 existing Penpot seeds contain hand-fabricated penpot_api_info and
high_level_overview tool results that assert facts the server never said,
which is how the model learned an API that does not exist. This adds four
schema files that make the seed corpus mechanically verifiable against the
real server instead.
- penpot_api_docs.md: 34 verbatim captures of high_level_overview and
penpot_api_info, each headed by the exact request that produced it. Every
penpot_api_info tool result in a seed must be a subset of lines of this
file, in original order. Records three places where the served docs
contradict the runtime (addFlexLayout/addGridLayout copy-paste in the Grid
section, flex.appendChild for grid children, withChildren vs
includeChildren), plus the createText() example that is the direct cause
of the production failure.
- penpot_system_prompt.md: the server's instructions block verbatim. Goes as
a system message into ~30% of the new seeds; it is the countermeasure to
the "don't pick your own colours" rule that produces the grey boxes.
- penpot_errors.md: the real error strings, including a section on silent
failures that raise nothing at all and are why the read-back invariant
exists.
- PENPOT_API_VERIFIED.md: the allow-list. No seed may reference a member
absent from it. Documents the four root causes (findShapeById arity 1,
no shape.layout, createText() returning null, the #B1B2B5 default fill),
the twelve anti-grey-box invariants, and the forbidden-pattern list the
linter checks.
Live re-verification of the error strings is still pending: the Penpot
plugin is not currently connected, so it is deferred to the gate 5 baseline
step, which needs the live connection anyway.
aleleba