docs(scale): correct F1 — table-facts RPC slowness is a generic plan + verified one-line fix

[BigSimmo]

Corrects the F1 finding in docs/scale-readiness-review.md after re-profiling live (read-only). My original F1 diagnosis was wrong, and the fix it recommended (rewrite the fuzzy disjunct to the % operator) is already on live and did not help.

What's actually happening

• Live match_document_table_facts_text already uses the bounded-CTE + % form. Each arm is fast in isolation (tsv @@ 0.36 ms, normalized_terms && 5.5 ms, trigram % 158 ms), and the full body with a literal query runs in 70 ms.
• But the RPC call is 5.3 s. Root cause: the function is LANGUAGE sql STABLE with SET search_path → non-inlinable → its body is planned once with an unknown $1, so the planner can't estimate trigram/tsv selectivity and picks near-seq-scan strategies. Every call pays that generic plan.
• Verified on live: SET plan_cache_mode = force_custom_plan drops it 5.3 s → ~1.1 s (≈4.8×).

The fix (pure performance — results byte-identical, no eval gate)

alter function public.match_document_table_facts_text(text, integer, uuid[], uuid)
  set plan_cache_mode = 'force_custom_plan';

Body-agnostic (targets the function by argument signature), so it does not collide with the separate schema.sql↔live body/return-signature drift on this RPC (that reconciliation belongs to the drift backlog). Same one-liner applies to the other non-inlined hybrid RPCs (memory-cards, index-units, embedding-fields). A full ≈75× fix (→ ~70 ms) needs converting to plpgsql + RETURN QUERY EXECUTE, after the drifted body is reconciled.

Why docs, not a migration

Applying to live needs the linked supabase CLI (operator credentials — not authenticated in this environment) and the migration policy forbids db push on this project's divergent history. The ALTER FUNCTION above is a safe, results-identical, one-line change you can run in the dashboard SQL editor or land as a committed migration when you next apply migrations.

Refs #339
🤖 Generated with Claude Code

[supabase]

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