docs(research): resolve deep-research-engine topic-1 (/deep-research trigging)

Operator reviewed the brief (S57) and approved as-is, then chose research-first
at the /trekplan research gate (option A: investigate only the genuinely-external
topic 1; fold local topics 2/3 into /trekplan exploration).

Topic 1 finding (validator-green; claude-code-guide + CC 2.1.196 binary + a real
local /deep-research run, all cited): /deep-research is a built-in *dynamic
workflow* (not a skill), outside the Skill-tool allowlist. Trigging is
prose-instruction only; the report lands inline in context with no on-disk
artifact (only the .js script is written). => the engine must be instruction-based
+ in-context transform, surface-only. Brief's v2.1.154+ / Pro-via-/config
constraints verified correct; SC3 ("dynamic workflows off -> fallback to swarm")
is correct as written (an earlier review note that called it a conflation rested
on a wrong premise and is retracted).

- docs/deep-research-engine-research.md: new, research-validator green strict.
- docs/deep-research-engine-brief.md: status draft->ready (operator-approved),
  research_status pending->complete (option-A decision recorded), Research Plan
  traceability note.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019ddpUq3MNQFoV5h3qYrVYj

docs/deep-research-engine-brief.md

@@ -4,10 +4,10 @@ brief_version: "2.2"
 task: "Opt-in /deep-research-motor for /trekresearch ekstern-fase"
 slug: deep-research-engine
 framing: refine
-status: draft
+status: ready
 brief_quality: complete
 research_topics: 3
-research_status: pending
+research_status: complete
 phase_signals_partial: true
 ---
 
@@ -51,6 +51,8 @@ phase_signals_partial: true
    `/trekresearch --project <dir> --local "Hva krever research-validator.mjs av research/NN-*.md?"`
 3. **Feature-deteksjon + fallback** — Hvordan oppdage om workflows er på, og hvor i fasen fallback-grenen bør sitte? Scope: local · Konfidens: middels · Kost: lav.
 
+> **Research-status (2026-06-30, operatør-beslutning «option A»):** Topic 1 (eneste ekte eksterne ukjente) er undersøkt → `docs/deep-research-engine-research.md` (validator-grønn). Funn: `/deep-research` er en innebygd **dynamic workflow** (ikke skill) → trigging KUN via prosa-instruksjon, output **inline i kontekst** (ingen on-disk-artefakt) → motoren må være instruksjons-basert + in-context transform. **SC3 er korrekt som skrevet** (`/deep-research` ER en dynamic workflow). Topic 2 (validator-skjema: `type/created/question` + `## Executive Summary`/`## Dimensions`, `dimensions ≥ 1`) og topic 3 (fallback-plassering) er lokale kode-spørsmål reklassifisert til `/trekplan`-utforskning. `research_status: complete` reflekterer denne beslutningen.
+
 ## Open Questions / Assumptions
 - Antar at `/deep-research`-rapporten kan reduseres til ≥ 1 dimensjon med per-påstand-sitater uten å bryte trianguleringen. Verifiseres i topic 2.
 - Uavklart om delegering skjer via instruksjon (trygt) eller programmatisk API (raskere) — topic 1 avgjør.