docs(ultraplan-local): remove ultra-cc-architect references (SC-6 doc-rydding)

Step 12 of v3.4.1 plan. Surgical line-by-line generalization of references
to the ultra-cc-architect plugin (no longer publicly distributed):

- CLAUDE.md: 8 hits → "opt-in upstream architect plugin (not bundled)"
- README.md: 9 hits including bare slug at line 646 (removed entirely);
  rephrased to "no longer publicly distributed" with the architecture/
  filesystem slot still supported by /ultraplan-local
- SECURITY.md: 1 hit → generalized "Opt-in upstream architect step"

CHANGELOG.md historical references preserved per brief; appended a
2026-05-04 note at top of [3.0.0] block stating the plugin is no longer
publicly distributed but the architecture/overview.md slot remains
supported for any compatible producer.

The architecture/overview.md filesystem contract (Handover 3, EXTERNAL,
drift-WARN) is unchanged — anyone implementing a compatible producer
can plug in.

361 tests still green (no regressions). doc-consistency pins for
/ultracontinue-local and Handover 7 § Lifecycle still pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plugins/ultraplan-local/README.md

@@ -27,7 +27,7 @@ Every artifact lives in one project directory: `.claude/projects/{YYYY-MM-DD}-{s
 |---|---|---|
 | `/ultrabrief-local` | **Capture intent** — intent, goal, non-goals, success criteria, and a research plan with explicit topics. Interactive only. | `brief.md` (task brief) |
 | `/ultraresearch-local` | **Gather context** — code state, external docs, community, risk. Makes NO build decisions. | `research/NN-slug.md` (research brief) |
-| `/ultraplan-local` | **Transform intent into an executable contract** — per-step YAML manifest, regex-validated checkpoints, verifiable paths. Plan-critic is a hard gate. Auto-discovers `architecture/overview.md` as priors when the `ultra-cc-architect` plugin is installed. | `plan.md` with Manifest blocks + `plan_version: 1.7` |
+| `/ultraplan-local` | **Transform intent into an executable contract** — per-step YAML manifest, regex-validated checkpoints, verifiable paths. Plan-critic is a hard gate. Auto-discovers `architecture/overview.md` as priors when an opt-in upstream architect plugin (not bundled) is installed. | `plan.md` with Manifest blocks + `plan_version: 1.7` |
 | `/ultraexecute-local` | **Execute the contract disciplined** — fresh verification, independent manifest audit, honest reporting. Does NOT compensate for weak plans — escalates. | `progress.json` + structured report + manifest-audit status |
 | `/ultrareview-local` | **Close the loop** — independent post-hoc reviewer reads `brief.md` and the diff produced by execute, runs brief-conformance + code-correctness reviewers in parallel, dedups via Judge Agent. Severity-tagged findings (Critical/High/Medium/Low/Info) feed back into planning via Handover 6. | `review.md` (`type: ultrareview`) with stable 40-char hex finding-IDs |
 
@@ -89,7 +89,7 @@ Or opt into auto-mode in `/ultrabrief-local` — it will run research and planni
 
 If review finds issues, feed `review.md` back into planning to produce a remediation plan: `/ultraplan-local --brief .claude/projects/2026-04-18-jwt-auth/review.md`. The remediation plan carries `source_findings: [<id>, ...]` in its frontmatter — full audit trail back to the consumed findings (Handover 6).
 
-For Claude-Code-specific architecture matching (matching brief+research to features like Hooks, Subagents, Skills, MCP), install the separate `ultra-cc-architect` plugin. It sits between research and plan — `/ultraplan-local` auto-discovers its output.
+An optional architect step can sit between research and plan — `/ultraplan-local` auto-discovers an `architecture/overview.md` produced by an opt-in upstream architect plugin (not bundled here; the architect plugin is no longer publicly distributed, but the `architecture/overview.md` filesystem slot remains available for any compatible producer).
 
 ## When to use it
 
@@ -200,7 +200,7 @@ Research uses up to 5 local agents (architecture-mapper, dependency-tracer, task
 
 Produces an implementation plan detailed enough for autonomous execution. **v2.0 breaking change:** requires `--brief` or `--project`. There is no longer an interview inside `/ultraplan-local` — use `/ultrabrief-local` first.
 
-After `brief-reviewer` validates the input brief, 6–8 Sonnet exploration agents analyze the codebase in parallel and merge findings into a synthesis. Optional research briefs (`--research`, or auto-discovered in `{project_dir}/research/`) enrich the plan; `architecture/overview.md` priors are loaded if the `ultra-cc-architect` plugin produced one. Opus then writes the plan with per-step YAML manifests, which `plan-critic` (9 dimensions) and `scope-guardian` adversarially review before handoff.
+After `brief-reviewer` validates the input brief, 6–8 Sonnet exploration agents analyze the codebase in parallel and merge findings into a synthesis. Optional research briefs (`--research`, or auto-discovered in `{project_dir}/research/`) enrich the plan; `architecture/overview.md` priors are loaded if an opt-in upstream architect plugin (not bundled) produced one. Opus then writes the plan with per-step YAML manifests, which `plan-critic` (9 dimensions) and `scope-guardian` adversarially review before handoff.
 
 Output:
 - With `--project <dir>`: `{dir}/plan.md`
@@ -517,7 +517,7 @@ Both arguments are required. No interactive prompt — headless-safe.
 
 All artifacts live under `.claude/projects/{YYYY-MM-DD}-{slug}/`.
 
-To insert a Claude-Code-specific architecture-matching step between research and plan, install the separate `ultra-cc-architect` plugin — `/ultraplan-local` auto-discovers its `architecture/overview.md` output as priors.
+An opt-in upstream architect plugin (not bundled) can insert a Claude-Code-specific architecture-matching step between research and plan — `/ultraplan-local` auto-discovers its `architecture/overview.md` output as priors when present.
 
 ### Example workflows
 
@@ -605,7 +605,7 @@ Validators (zero npm deps, hand-rolled YAML subset):
 | `lib/validators/research-validator.mjs` | research-brief frontmatter (confidence ∈ [0,1], dimensions ≥ 1) + body sections; `--dir` mode validates a whole `research/` folder |
 | `lib/validators/plan-validator.mjs` | wraps plan-schema + manifest-yaml; enforces v1.7 step heading, manifest count match, and forbidden-narrative-form denylist (`### Fase/Phase/Stage/Steg N`) — replaces the Phase 5.5 grep checks |
 | `lib/validators/progress-validator.mjs` | progress.json shape (schema_version, status enum, current_step in range) + resume-readiness check |
-| `lib/validators/architecture-discovery.mjs` | EXTERNAL CONTRACT — drift-WARN, never drift-FAIL. Discovers `architecture/overview.md` (owned by the separate `ultra-cc-architect` plugin) and tolerates non-canonical filenames with warnings. |
+| `lib/validators/architecture-discovery.mjs` | EXTERNAL CONTRACT — drift-WARN, never drift-FAIL. Discovers `architecture/overview.md` (owned by an opt-in upstream architect plugin, not bundled) and tolerates non-canonical filenames with warnings. |
 
 Each module exposes a CLI: `node lib/validators/<name>.mjs --json <path>` returns structured `{valid, errors, warnings, parsed}`. Commands invoke the CLI as their schema check.
 
@@ -615,7 +615,7 @@ Borrowed pattern from `llm-security` (commit `97c5c9d`); extending the plugin sh
 
 ### Handover contracts
 
-`docs/HANDOVER-CONTRACTS.md` is the single source of truth for the file formats that pass between the four pipeline commands (brief → research → plan → execute). When you fork the plugin or extend a stage, that document tells you what every producer must write and what every consumer is allowed to assume. It also documents the *external* contract for `architecture/overview.md` (owned by the separate `ultra-cc-architect` plugin) — discovery only, drift-warn never drift-fail.
+`docs/HANDOVER-CONTRACTS.md` is the single source of truth for the file formats that pass between the four pipeline commands (brief → research → plan → execute). When you fork the plugin or extend a stage, that document tells you what every producer must write and what every consumer is allowed to assume. It also documents the *external* contract for `architecture/overview.md` (owned by an opt-in upstream architect plugin, not bundled) — discovery only, drift-warn never drift-fail.
 
 ### PreCompact resume integrity (CC v2.1.105+)
 
@@ -643,7 +643,7 @@ Or enable directly in `~/.claude/settings.json`:
 }
 ```
 
-For Claude-Code-specific architecture matching (between research and plan), also enable `ultra-cc-architect@ktg-plugin-marketplace`.
+An optional architect step between research and plan was previously available via a separate plugin; that architect plugin is no longer publicly distributed. The `architecture/overview.md` filesystem slot remains supported by `/ultraplan-local` for any compatible producer.
 
 ## Cost profile
 
@@ -744,11 +744,11 @@ schema drift.
 
 ### Disable the architect bridge
 
-`/ultraplan-local` auto-discovers `architecture/overview.md` if the
-separate `ultra-cc-architect` plugin produced one. To suppress this,
-either don't install `ultra-cc-architect`, or set `architecture/`
-absent in your project directory. Discovery is additive — missing
-file is fine, no error.
+`/ultraplan-local` auto-discovers `architecture/overview.md` if an
+opt-in upstream architect plugin (not bundled) produced one. To
+suppress this, leave the `architecture/` directory absent from your
+project directory. Discovery is additive — missing file is fine, no
+error.
 
 ## Contributing