feat(voyage)!: marketplace handoff — rename plugins/ultraplan-local to plugins/voyage [skip-docs]

Session 5 of voyage-rebrand (V6). Operator-authorized cross-plugin scope.

- git mv plugins/ultraplan-local plugins/voyage (rename detected, history preserved)
- .claude-plugin/marketplace.json: voyage entry replaces ultraplan-local
- CLAUDE.md: voyage row in plugin list, voyage in design-system consumer list
- README.md: bulk rename ultra*-local commands -> trek* commands; ultraplan-local refs -> voyage; type discriminators (type: trekbrief/trekreview); session-title pattern (voyage:<command>:<slug>); v4.0.0 release-note paragraph
- plugins/voyage/.claude-plugin/plugin.json: homepage/repository URLs point to monorepo voyage path
- plugins/voyage/verify.sh: drop URL whitelist exception (no longer needed)

Closes voyage-rebrand. bash plugins/voyage/verify.sh PASS 7/7. npm test 361/361.

plugins/voyage/docs/subagent-delegation-audit.md

@@ -0,0 +1,129 @@
+# Subagent Delegation Audit — Main-Context Pressure Analysis
+
+**Status:** Exploratory brief — findings + options, not a decision
+**Date:** 2026-04-19
+**Scope:** trekplan v2.3.2, all six user-facing commands
+
+## Problem
+
+Main context fills up quickly during trekplan runs. The plugin's
+design principle is Context Engineering — the main context should
+**orchestrate**, subagents should **execute**. In practice, the exploration
+phases do delegate aggressively, but the **synthesis and writing phases
+remain inline**, which is where the bulk of heavy reading and reasoning
+actually happens.
+
+## Verified findings
+
+### 1. Exploration is already well-delegated
+
+Agent-spawn density per command (nominal):
+
+| Command                  | Agents spawned                                                    |
+|--------------------------|-------------------------------------------------------------------|
+| trekresearch      | ~9–14 (5 local + 4 external + 1 bridge + up to 2 follow-ups)      |
+| trekplan          | ~10 (6 initial + conditional research-scout + up to 3 deep-dives) |
+| trekbrief         | 1–3 (brief-reviewer per iteration, max 3)                         |
+| trekexecute       | 0 (explicit no-agent rule)                                        |
+| voyage-skill-author-local | 3 (concept-extractor → skill-drafter → ip-hygiene-checker)        |
+
+This part is healthy.
+
+### 2. Synthesis and writing is inline
+
+The main context does the heavy cognitive work after swarm completion:
+
+- **`commands/trekplan.md:483–498` (Phase 7 Synthesis):**
+  "Read all agent results carefully" + "Build a mental model of the codebase
+  architecture" + "Catalog reusable code" + "Integrate research findings".
+  This forces 6–10 agent outputs to remain resident in main context simultaneously.
+
+- **`commands/trekplan.md:499–548` (Phase 8 Deep Planning):**
+  Main context writes the entire plan.md from scratch, including all required
+  sections, quality standards, and file-path validation.
+
+- **`commands/trekresearch.md:302–323` (Phase 6 Triangulation):**
+  Explicitly labelled "the KEY phase that makes trekresearch more than
+  aggregation". Dimension-by-dimension comparison of local vs external
+  findings, contradiction flagging, confidence rating — all inline.
+
+- **`commands/trekresearch.md:325–341` (Phase 7 Synthesis):**
+  Writes the research brief inline using the template.
+
+### 3. Root cause — v2.4.0 foreground migration
+
+Each command carries a `> **Why foreground?**` block
+(`trekplan.md:330`, `trekresearch.md:192`) documenting that the
+background orchestrators were removed because agents spawned from background
+orchestrators silently degraded. The swarm-spawn logic was lifted into the
+main context — but so was the synthesis logic the orchestrators used to
+carry. The "summarizer" link is missing.
+
+## Candidate interventions
+
+Presented as options, ordered by estimated main-context savings. Numbers
+are rough estimates based on the size of the phase bodies — not measured.
+
+| # | Intervention                                                        | Target phase                        | Rough saving |
+|---|---------------------------------------------------------------------|-------------------------------------|--------------|
+| 1 | `synthesis-agent` — digests all exploration outputs into findings + reuse catalog + gaps | trekplan Phase 7                   | 40–50%       |
+| 2 | `plan-writer-agent` — writes plan.md from synthesis + template      | trekplan Phase 8                   | part of #1   |
+| 3 | `triangulation-synthesizer` — per-dimension local vs external diff + confidence rating | trekresearch Phase 6               | 25–30%       |
+| 4 | `research-brief-writer` — writes research brief from triangulation output | trekresearch Phase 7               | part of #3   |
+
+## Tradeoffs (important)
+
+- **Iteration friction.** A synthesis- or writer-agent does not see the
+  live conversation. If the user wants to push back on the plan ("split
+  step 3 in two", "re-phrase the risks"), refinement still has to happen
+  in main context. Delegation works best for the first pass; the revision
+  loop is harder to delegate.
+
+- **Adversarial review still needs main.** `plan-critic` and
+  `scope-guardian` already return findings to main context — which then
+  has to act on them. If the plan was written by an agent, main must
+  either re-invoke the writer agent with critic feedback, or absorb the
+  plan back in to revise it. Neither is free.
+
+- **Artifact quality gates.** The current inline phases enforce
+  quality rules (e.g., "every file path must exist in the codebase").
+  A writer-agent needs the same codebase context the exploration agents
+  had — re-delivering that context to the writer burns tokens the
+  delegation was meant to save.
+
+- **Debuggability.** Inline synthesis is inspectable in the transcript.
+  Agent-synthesis hides the reasoning inside the agent's return message —
+  fine when it works, harder to diagnose when it doesn't.
+
+## Recommendation (tentative)
+
+If only one change is made, **intervention #1 (synthesis-agent for
+trekplan Phase 7)** has the largest ROI. It isolates the heaviest read
+(all 6–10 agent outputs) behind a summarizer, and its output — a compact
+findings document — is small enough to keep resident for Phase 8 planning
+and Phase 9 review.
+
+Intervention #3 is a smaller-scope and lower-risk proof-of-concept
+that could validate the pattern before touching the main planner.
+
+## Open questions
+
+1. Should the synthesis-agent write to disk (`synthesis.md` alongside
+   `plan.md`) for inspectability, or return in-memory?
+2. Does the adversarial review phase (plan-critic + scope-guardian) need
+   access to the full exploration outputs, or is the synthesis artifact
+   enough?
+3. Is there a way to measure current main-context usage per phase so the
+   savings estimates above can be replaced with real numbers before
+   committing to changes?
+4. Does this interact with `REMEMBER.md`'s note that "trekplan schema-drift
+   on 4.7 produces Phase-plans instead of v1.7 step-schema"? A writer-agent
+   might either help (isolated, more controllable) or hurt (another layer
+   where drift can happen) the schema-drift problem.
+
+## Out of scope for this brief
+
+- Implementation details of the new agents
+- Changes to trekexecute (no-agent by design)
+- Changes to trekbrief Phase 3 interview (must be inline to drive
+  user dialogue)