core/docs/analysis/field-wedge-ablation-result-2026-06-04.md

The field-reasoner wedge ablation — result: C3 (decoration on this domain)

This records the outcome of the falsifiable experiment designed in field-reasoner-wedge-design-and-falsification-2026-06-04.md. The verdict is the dossier's sanctioned negative: the field reads correctly but is decoration here. That is a success — it answers the field-as-reasoner question with evidence instead of deferring it.

What was measured

Two readings of the same forward-substitutable quantitative-relational micro-domain (additive / part-whole), scored against an independent arithmetic oracle:

• Field reader (generate/relational_field_reader.py) — reads TEXT into conformal points on the e1 number line; additive relations are conformal translator versors; the answer reads back by projective dehomogenization. (The geometric SUT.)
• Symbolic reader (generate/relational_symbolic_reader.py) — a competent, code-disjoint reading by plain integer arithmetic; no algebra (INV-27 disjoint).

The ablation (evals/relational_metric/ablation.py) runs both through the real verify_tier2_agreement gate and asks the only questions that matter.

Result

Measurement	Value	Meaning
field_wrong_commits	[]	wrong=0 holds — the field never commits a bad integer (the per-step drift guard refuses instead).
field_caught_symbolic_errors	[]	The field caught zero comprehension errors the symbolic reader made. (Measurement #2 = fail.)
field_lost_coverage	[rm-v1-0015]	The only admitted-set change is the field refusing a correct answer at the precision ceiling — a liability, not signal.
per-class diversity	0 everywhere	On every committable class the readers AGREE and are BOTH CORRECT: disagree=0, double_fault=0. (Measurement #3 = no diversity.)
verdict	C3	The field is decoration / a coverage liability on this domain.

Why — the load-bearing insight

On forward-substitutable relations, geometric translation is arithmetic addition. versor_apply(T_δ, embed[x]) = embed[x+δ] is exactly x + δ. There is no metric over-determination — no betweenness, incidence, or continuous-constraint structure — for the field to exploit that a competent symbolic reader lacks. So the two readings are redundant (the common-mode the dossier predicted via Knight–Leveson), and agreement adds no independent soundness signal. The field's one genuine marginal check (over-determination coherence) is matched by the symbolic reader's over_determined_conflict refusal, so even there it is not unique. And the field's precision ceiling makes it a strict coverage liability versus pure integer arithmetic.

This is the deductive-logic finding's twin: there, logic was combinatorial not metric, so the field could not earn it; here, the metric domain is arithmetically trivial, so the geometry adds nothing. The field earns a reasoning role only where geometry genuinely exceeds the symbolic alternative — not yet demonstrated on any built domain.

What this changes

• Field-as-reasoner is NOT earned. No field vote enters any serving or capability path. The field stays a servant (its existing cognition-turn role). No "the field reasons" claim is made.
• The capability path is symbolic (C3). The symbolic reader is correct (15/15 here, including the case the field refuses). Shipping quantitative capability safely is the dossier's Phase 3+ on the symbolic path — two code-disjoint symbolic readings agreeing + independent/sealed gold (one reader alone is the resolve_pooled risk). Not built here; this slice answered the experiment, it did not ship serving.
• The t2_precision lever stays dormant for this domain — there is no genuine second derivation to feed it (field⟂symbol is common-mode here).

What stays (all load-bearing, none reverted)

• The f64 conformal foundation (Phase 0A) — net infrastructure hardening.
• The reader-lineage firewall + INV-27 (Phase 0B/0C) — backs any future agreement gate.
• The field reader + relational-metric lane — a real wrong=0 demonstration that the field can read (Phase W.1), and a valid 3rd independently-golded panel domain.
• The symbolic reader + ablation instrument — the C3 reader and a reusable decoration test for the next domain.

The honest next bet (dedicated research, not the near-term sequence)

Field-as-reasoner remains an open question for a domain where geometry genuinely beats arithmetic: continuous / over-determined / multi-constraint structure (relative position, betweenness, incidence among many points, ratio as cross-ratio on a non-degenerate frame) — where a symbolic step-arithmetic reader and a field constraint reading could genuinely diverge, and agreement would be a real second derivation. Until such a domain is built and the ablation shows field_caught_symbolic_errors > 0, the field stays a servant. Two negative domains (logic: combinatorial; additive: trivial) now bound the search: the field needs metric-nontrivial, arithmetically-hard structure.