Two diet/teaching changes to elements.md, both motivated by today's
ab-v4 smoke results:
(a) parent_id teaching — minimax-m2.7 invented "members-section" /
"canvas" as parent_id values on its multi-tool composite output,
then every one of its 14 tags failed apply with "parent_id X not
found in document". Same pattern as yesterday. Adds an explicit
rule near the top of elements.md (right under the multi-tool
banner) — `parent_id` is REAL or OMITTED, never invented. The
`<page>` / `<panel>` / `<sidebar>` placeholders in the cookbook
recipes are documentation conventions; in actual output, OMIT
the field. Names the failure mode by reproducing the error
message format so models learn to avoid it.
(b) Phase 3 token diet — strip ". Different from <tool> (...)"
disambiguation suffixes from the PREFER list (22 entries had
them, ~80-200 chars each = ~2.5kb / ~625 tokens saved). The
primary keyword + tool-name + capability description survives
intact; the cross-references pointing at sibling tools get
dropped. Risk: slight increase in wrong-tool routing on
ambiguous prompts. Worth it for the size reduction; the
decision tree alone still shows the tool family in context.
Verified by mechanical diff — perl in-place edit, then visual
review confirms no other content was touched. 3785 vitest pass,
format clean, tsc silent.
Net effect on T-prompt size (chars / 4 estimate):
T + composite + mobile: was 17,930 → now 17,475 (-455 chars)
T + composite + dashboard: was 18,437 → now 17,983 (-454 chars)
T + obvious + dashboard: ~14,009 → ~13,556 (-453 chars)
Per-arm savings are smaller than the raw 2.5kb trim because (a)
adds ~700 chars of parent_id teaching. Net win: ~450 chars / ~110
tokens per call. Modest but compounds across 520+ ab-v4 runs.
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