chore(cleanup): R-b R3 — profiles, phase signals and the effort dialog removed, one fixed path per command

The four profiles, the resolver, the profile validator and docs/profiles.md go;
/trekbrief Phase 3.5 and the brief's phase_signals checks go (an older brief's
key is ignored); MANIFEST_PROFILE_DRIFT and profile_used go. Every Profile,
Composition rule, Sequencing gate and High-effort section leaves the commands.
Decision 209: /trekresearch runs the full swarm with contrarian-researcher as
wave 2 every run; /trekreview and the coordinator run all four passes with no
high-effort normalization. Voyage agents are spawned with no model (their own
model: opus applies); the two built-in spawns pass model "opus". --profile
stays in the parser as a retired flag that swallows its value. §Model & effort
moves to docs/architecture.md; the sequencing-gate eval case goes.

Files removed: 44 (43 from the R3 list + tests/commands/trekreview.test.mjs,
whose every test pinned removed text). Files edited: 43.
Tests: 2467 (2466 pass / 0 fail / 1 skipped) before, 2309 (2309 pass / 0 fail /
0 skipped) after. Durable check: all three groups green, none pending.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/architecture.md

@@ -34,9 +34,7 @@ Doc-consistency test at `tests/lib/doc-consistency.test.mjs` pins agent-table co
 
 ## Architecture
 
-**Brief:** 7-phase workflow: Parse mode → Create project dir → Phase 3 completeness loop (section-driven, no question cap) → Phase 3.5 per-phase effort dialog (v5.1) → Phase 4 draft/review/revise with `brief-reviewer` as stop-gate (max 3 iterations; gate = all dimensions ≥ 4 and research plan = 5) → Finalize (`brief.md` on pass, or `brief_quality: partial` on cap/force-stop) → Manual/auto opt-in. Always interactive. Auto mode runs research + plan inline in the main context (v2.4.0).
-
-**Phase 3.5 (v5.1) — adaptive-depth signals:** Between Phase 3 completeness exit and Phase 4 draft, the operator commits an effort level (`low | standard | high`) and an optional `model` (`sonnet | opus | fable`) per downstream phase (`research`, `plan`, `execute`, `review`) via 4 tier-coupled `AskUserQuestion` calls. The choices land in `brief.md` frontmatter as `phase_signals:` (a list of `{phase, effort?, model?}` entries) when committed, or `phase_signals_partial: true` when the operator force-stops. `brief_version: 2.1` activates the **sequencing gate**: validator emits `BRIEF_V51_MISSING_SIGNALS` if a 2.1-versioned brief lacks both fields. Downstream commands surface a friendly hint pointing back to `/trekbrief` — enforcement is validator-only. Composition is documented prose in each downstream command's `## Composition rule (v5.1)` section: `brief.phase_signals[phase] > profile.phase_models[phase]`. The brief signal wins per-phase when present; the profile fills gaps. `effort == low` activates each command's existing `--quick`-equivalent code-path (`/trekexecute` low effort = one session at a time). High-effort behavior is deferred to v5.1.1 per brief Non-Goal.
+**Brief:** 7-phase workflow: Parse mode → Create project dir → Phase 3 completeness loop (section-driven, no question cap) → Phase 4 draft/review/revise with `brief-reviewer` as stop-gate (max 3 iterations; gate = all dimensions ≥ 4 and research plan = 5) → Finalize (`brief.md` on pass, or `brief_quality: partial` on cap/force-stop) → Manual/auto opt-in. Always interactive. Auto mode runs research + plan inline in the main context (v2.4.0).
 
 **Research:** Foreground workflow (v2.4.0): Parse mode → Interview → Parallel research swarm (5 local + 4 external + 1 bridge, spawned from main context) → Follow-ups → Triangulation → Synthesis + brief. With `--project`, writes to `{dir}/research/NN-slug.md`.
 
@@ -97,6 +95,47 @@ Which native Claude Code primitive each pipeline step runs on today, and the alt
 
 **Legend:** *production* = wired and active · *not wired* = considered, deferred (delegated orchestrator, the `AskUserQuestion` brief engine).
 
+## Model & effort
+
+`opus`, `sonnet`, and `fable` are model **aliases**, not pinned ids. On the
+Anthropic API (verified 2026-10-02 against the Claude Code model-config docs)
+the `opus` alias resolves to **Opus 5.5** and `sonnet` to **Sonnet 5.5**, both
+with default reasoning effort **`medium`**; `fable` resolves to **Fable 5.1**
+(the most capable model in Claude Code), whose default reasoning effort is
+**`high`**. Other providers resolve `opus` and `sonnet` to other versions.
+
+**Reasoning effort inherits from the session.** Fable 5.1's default reasoning
+effort is `high`, NOT xhigh, and Claude Code saves effort per model, so a level
+saved for one model does not carry to another. To run Fable 5.1 at xhigh,
+choose it explicitly: `/effort xhigh`, `--effort xhigh`, or
+`CLAUDE_CODE_EFFORT_LEVEL`.
+
+**Native `effort:` on agents.** Voyage sets the reasoning axis statically on
+selected agents, overriding the session level:
+
+- **Nine agents pin `high`:** the retrieval agents `task-finder`,
+  `git-historian`, `dependency-tracer`, `architecture-mapper`, the
+  adversarial-reasoning agents `plan-critic`, `risk-assessor`,
+  `contrarian-researcher`, `review-coordinator`, and `/trekexecute`'s step
+  helper `step-implementer`. No agent pins below `high`
+  (operator rule, 2026-10-05: standard is Opus 5.5 at effort High).
+- **All other agents:** unset → inherits the session's effort level (a session
+  that nothing sets runs at its model's default — `medium` on Opus 5.5).
+
+**Every agent is pinned `model: opus`.** The pin is set in each agent's
+frontmatter (operator decision, commit `40d8742`). The operator wants Opus on
+all Voyage work and accepted the roughly fivefold sub-agent cost against
+Sonnet. The glue, mechanical, retrieval and dormant roles were reconsidered
+for a Sonnet downgrade (operator, 2026-06-20) and kept on Opus: the pin stays
+firm.
+
+Native-effort precedence (harness): env `CLAUDE_CODE_EFFORT_LEVEL` > frontmatter
+`effort:` > session setting > model default, and a `maxEffortLevel` setting or
+an organization effort cap still limits the result. `MAX_THINKING_TOKENS=0` has
+no effect on Opus 5.5, Sonnet 5.5 or the Fable models: thinking cannot be turned
+off there. `availableModels` restricts which models can be selected — it does
+**not** bound effort.
+
 ## State
 
 All artifacts in one project directory (default):