docs(voyage): S7 (W1/CC-26 gate) — T1 feasibility probe + measurement design

Staged gate execution (operator-chosen): cheap live feasibility probe + design
doc; expensive head-to-head specified but NOT run.

Probe (CC 2.1.181 interactive): depth-2 sub-agent nesting works (main->L1->L2,
both have Agent tool), no degradation; v2.4.0 'no Agent for sub-agents' premise
confirmed false. Depth cap (<=5) moot for Voyage (needs depth 2). NEW finding:
auto-mode proliferation classifier polices agent fan-out — a classifier-
interference risk unique to delegation.

CC-26 recommendation (operator gates verdict): lean NO on wholesale delegated
orchestration; only defensible path is a narrow opt-in synthesis-agent PoC
proven by delta main-context tokens. CC-27 (Workflow, S8) untouched.

New: docs/T1-cc26-delegated-orchestration.md (gate evidence + full bake-off
design with thresholds + cheaper synthesis-agent PoC). Matrix: CC-26 row +
S7 resolutions + open-question/T1 pointers updated. Docs-only; no code/schema.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LqBYc8Ltrk7LipyJmGxXiB

docs/cc-upgrade-2.1.181-decision-matrix.md

@@ -122,7 +122,7 @@ S4 implemented the four scope items above. TDD: a failing test was written first
 
 | ID | Change (version) | Type | Voyage relevance | Decision | Rationale |
 |----|------------------|------|------------------|----------|-----------|
-| **CC-26** | Sub-agents spawn sub-agents ≤5 deep (**2.1.172**, verified) — the design response to CC-01 | NEW | Could restore *delegated* orchestration: an orchestrator sub-agent spawns the swarm; synthesis/writing delegated (the "missing summarizer link" in `docs/subagent-delegation-audit.md`). Frees main-context tokens | **EVALUATE** (empirical) | "Can spawn 5 deep" ≠ "Voyage's orchestrator→6-agent-swarm pattern performs well." Design + run a Q3-style measurement (reuse `scripts/q3-cache-prefix-experiment.mjs` harness pattern) before re-architecting. Depth cap (5) may bound nested pipelines. **Highest-value, highest-risk item.** |
+| **CC-26** | Sub-agents spawn sub-agents ≤5 deep (**2.1.172**, verified) — the design response to CC-01 | NEW | Could restore *delegated* orchestration: an orchestrator sub-agent spawns the swarm; synthesis/writing delegated (the "missing summarizer link" in `docs/subagent-delegation-audit.md`). Frees main-context tokens | **EVALUATE → lean NO (S7)** | "Can spawn 5 deep" ≠ "Voyage's orchestrator→6-agent-swarm pattern performs well." **S7 (2026-06-18, GATE):** feasibility probed cheaply — depth-2 nesting works, no degradation; depth cap moot (Voyage needs depth 2); NEW finding = auto-mode proliferation classifier polices agent fan-out (risk unique to delegation). On cost/benefit, **wholesale delegation NOT recommended**; the only defensible path is a narrow opt-in synthesis-agent PoC, proven by Δ main-context tokens. Operator gates verdict. Full bake-off designed but NOT run. See `docs/T1-cc26-delegated-orchestration.md` + §S7. |
 | **CC-27** | Dynamic Workflows / Workflow tool — orchestrates tens–hundreds of agents (**2.1.154**, verified); keyword `workflow`→`ultracode` (2.1.160); `agent()` attribution headers (2.1.174) | NEW | Voyage **hand-rolls** swarm/wave/pipeline orchestration in command prose — the Workflow tool is a native primitive for exactly this | **EVALUATE** (strategic) | The biggest identity decision: adopt Workflow as Voyage's execution substrate, or stay prose-orchestrated for portability/control? Tradeoffs: native concurrency + pipelining + budget control vs. dependency on a newer primitive + loss of fine-grained prose control + opt-in/billing semantics. Prototype one pipeline (e.g. `/trekreview`'s reviewer swarm) as a Workflow and compare. |
 | **CC-28** | `TaskCreate` reliability — auto-repairs malformed input, schema in errors (2.1.163/169) | FIX | `TaskCreate`/`TaskUpdate` are in `trekplan`/orchestrator frontmatter but not actively used in command logic | **DEFER** | Becomes relevant only if W1 adopts task-graph orchestration. Tie to CC-26/27 outcome. |
 | **CC-29** | `subagent_type` matching now case/separator-insensitive (2.1.140); multiple `Agent(...)` types in `tools:` no longer dropped (2.1.147); subagent transcript/backgrounding fixes (2.1.178) | FIX | improves DX of any delegated-orchestration design | **SHIP** (verify) | Free robustness. Confirm Voyage's agent `tools:` grants (none currently declare multiple `Agent(...)` types) and `subagent_type` references are unaffected. |
@@ -130,6 +130,36 @@ S4 implemented the four scope items above. TDD: a failing test was written first
 
 ---
 
+## S7 resolutions (W1 / CC-26 gate — 2026-06-18, operator-gated)
+
+S7 was the first W1 gate. Operator chose a **staged** execution: cheap live feasibility probe +
+measurement-design doc; the expensive head-to-head comparison was specified but **not run**.
+
+- **Feasibility (measured).** A recursive `general-purpose` agent chain in this CC 2.1.181
+  interactive session confirmed: depth-2 nesting works (`main → L1 → L2`; both children report the
+  Agent tool available), and the nested sub-agent returned a real, well-formed result — **no silent
+  degradation** at depth 2. The v2.4.0 premise ("harness does not expose Agent to sub-agents") is
+  confirmed false at the interactive sub-agent level.
+- **Depth cap moot.** The ≤5 cap was never reached; the recursion stopped at L2→L3 via the
+  **auto-mode permission classifier** (policy denial: "uncontrolled agent proliferation"), not the
+  nesting limit. Voyage's needed pattern is depth 2, so the cap does not bind this gate.
+- **NEW finding — proliferation classifier.** Auto/bypass modes actively deny purposeless agent
+  fan-out. A delegated orchestrator spawning a 6–10-agent swarm from inside a sub-agent under
+  `auto`/`bypassPermissions` is exactly that shape — a classifier-interference risk **unique to
+  delegation** that inline orchestration does not carry, and a new silent-degradation surface if a
+  mid-pipeline spawn is denied. Must be in any future delegated-spawn test matrix.
+- **CC-26 recommendation (operator gates verdict).** Lean **NO** on wholesale delegated
+  orchestration: feasibility is no longer the blocker, so the gate turns on cost/benefit, which is
+  unfavourable (delegation's only upside is main-context relief, against wall-time loss, context
+  re-delivery cost, the audit's iteration/adversarial-review/debuggability tradeoffs, and the new
+  classifier risk). The only defensible win is a **narrow opt-in synthesis-agent** (delegate just
+  trekplan Phase 7's heaviest inline read), adopted only if a measured Δ main-context ≥ 30% with no
+  quality loss materialises. CC-27 (Workflow tool, S8) is the more promising substrate question and
+  is untouched.
+- **Artifact.** `docs/T1-cc26-delegated-orchestration.md` — full gate evidence, the §5 full
+  bake-off design (thresholds POSITIVE/NEGATIVE/INCONCLUSIVE), and the §6 synthesis-agent PoC, all
+  ready to run if the operator greenlights pursuing delegation.
+
 ## Sequencing
 
 ```
@@ -151,13 +181,13 @@ Incremental (W3):   CC-11/CC-14/CC-15 as small, independently-shippable hardenin
 ## Open questions (need operator or empirical answer)
 
 1. **W1 identity:** does Voyage adopt the Workflow tool as substrate, or stay prose-orchestrated? (CC-27)
-2. **W1 perf:** does delegated orchestration (orchestrator sub-agent → swarm) beat inline at Voyage's scale? (CC-26 — empirical)
+2. **W1 perf:** does delegated orchestration (orchestrator sub-agent → swarm) beat inline at Voyage's scale? (CC-26 — empirical) — **S7: feasibility YES, but lean NO on wholesale adoption; see §S7.**
 3. **W2 effort model:** map `phase_signals` onto native `effort:`, or keep bespoke? (CC-22 — gates v5.4)
 4. **CC-08:** is GH #36071 (hooks in headless) fixed? Determines whether the safety-preamble can relax.
 
 ## Empirical tests required
 
-- **T1 (CC-26):** orchestrator-sub-agent spawns the planning swarm vs. inline baseline — wall-time, quality, token cost, depth-cap behavior. Harness: extend `scripts/q3-cache-prefix-experiment.mjs` pattern.
+- **T1 (CC-26):** orchestrator-sub-agent spawns the planning swarm vs. inline baseline — wall-time, quality, token cost, depth-cap behavior. Harness: extend `scripts/q3-cache-prefix-experiment.mjs` pattern. — **S7: feasibility half RUN** (depth-2 works, no degradation, cap moot, proliferation-classifier risk found); **perf half DESIGNED, NOT run** (full bake-off + cheaper synthesis-agent PoC specified in `docs/T1-cc26-delegated-orchestration.md` §5/§6).
 - **T2 (CC-27):** reimplement `/trekreview`'s reviewer swarm as a Workflow; compare control, cost, and output fidelity vs. prose orchestration.
 - **T3 (CC-04/CC-31):** research-agent MCP degradation under `--strict-mcp-config`; worktree parallel-wave behavior under tightened bg-isolation.