feat: Orquestra - sequential orchestration runtime

- Context isolation: fresh Pi process per stage (run_stage.py)
- Gate enforcement: blocks close without approved gates
- Auto commit/push on feature close (close_feature.py)
- Write restrictions: only allowed directories (ALLOWED_WRITE_DIRS)
- Pi extension: orquestra-status with /orquestra-stage command
- Documentation: context-handoff.md, updated README
- Scripts: agent_status.py, verify.sh, install.sh updated

harness/agents.matrix.yml

@@ -56,6 +56,14 @@ roles:
       - regression_checks
       - emit_qa_verdict
 
+  documenter:
+    can_edit: ["work/artifacts/", "docs/", "README.md", "HOWTO.md", "platforms/pi/README.md", "harness/contracts/"]
+    cannot_edit: ["src/", "tests/", "backlog/features.json:status"]
+    responsibilities:
+      - document_changes_when_needed
+      - update_docs_api_contracts_user_facing_notes
+      - produce_documenter_evidence
+
 anti_cheat:
   - "Implementer cannot promote feature to done"
   - "Done requires reviewer/security/qa approved artifacts"

harness/contracts/evidence.schema.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://json-schema.org/draft/2020-12/schema",
-  "$id": "https://arnes.local/evidence.schema.json",
+  "$id": "https://orquestra.local/evidence.schema.json",
   "title": "Gate Evidence",
   "type": "object",
   "required": ["feature_id", "agent", "verdict", "summary", "evidence", "timestamp"],

harness/contracts/handoff.md

@@ -5,11 +5,20 @@ Los agentes **no** devuelven código en chat. Deben escribir a disco y responder
 - `done -> <ruta>`
 - `blocked -> <ruta>`
 
+## Contexto mínimo por stage
+Cada stage recibe solo:
+1. Los archivos listados en `harness/workflow.stages.yml` como `input`.
+2. El artefacto del stage anterior cuando el workflow lo declare.
+3. La memoria Engram que el leader seleccione explícitamente para ese stage.
+
+No se considera válido pasar todo el chat anterior como contexto operativo. Si un stage necesita más información, debe pedir una ruta o artefacto concreto y bloquear hasta tenerlo.
+
 ## Rutas estándar por feature
 - `work/artifacts/<feature_id>/implementer.md`
 - `work/artifacts/<feature_id>/reviewer.json`
 - `work/artifacts/<feature_id>/security.json`
 - `work/artifacts/<feature_id>/qa.json`
+- `work/artifacts/<feature_id>/documenter.md` (opcional; requerido solo si cambiaron docs/API/contratos/comportamiento user-facing)
 - `work/artifacts/<feature_id>/leader-close.json`
 
 ## Campos mínimos de artefactos JSON de gate

harness/model-routing.yml

@@ -0,0 +1,23 @@
+version: 1
+
+# Sequential role model hints for Pi. The parent session changes model before
+# each stage when a different model is desired. No parallel agents/subagents.
+roles:
+  leader:
+    model: default
+    reasoning: medium
+  architect:
+    model: strong
+    reasoning: medium
+  implementer:
+    model: default
+    reasoning: medium
+  reviewer:
+    model: strong
+    reasoning: low
+  security:
+    model: strong
+    reasoning: medium
+  qa:
+    model: default
+    reasoning: low

harness/workflow.stages.yml

@@ -15,38 +15,85 @@ stages:
   - name: design
     owner: architect
     optional: true
+    input:
+      - work/current.md
+      - spec/product.md
+      - spec/tech.md
+      - spec/acceptance.md
     output:
       - work/artifacts/<feature_id>/architect.md
 
   - name: build
     owner: implementer
+    input:
+      - work/current.md
+      - spec/product.md
+      - spec/tech.md
+      - spec/acceptance.md
+      - work/artifacts/<feature_id>/architect.md
     output:
       - work/artifacts/<feature_id>/implementer.md
 
   - name: review_gate
     owner: reviewer
     required: true
+    input:
+      - work/current.md
+      - spec/acceptance.md
+      - work/artifacts/<feature_id>/implementer.md
     output:
       - work/artifacts/<feature_id>/reviewer.json
 
   - name: security_gate
     owner: security
     required: true
+    input:
+      - work/current.md
+      - work/artifacts/<feature_id>/implementer.md
+      - work/artifacts/<feature_id>/reviewer.json
     output:
       - work/artifacts/<feature_id>/security.json
 
   - name: qa_gate
     owner: qa
     required: true
+    input:
+      - work/current.md
+      - spec/acceptance.md
+      - work/artifacts/<feature_id>/implementer.md
+      - work/artifacts/<feature_id>/reviewer.json
+      - work/artifacts/<feature_id>/security.json
     output:
       - work/artifacts/<feature_id>/qa.json
 
+  - name: document
+    owner: documenter
+    optional: true
+    when: docs/API/contracts/user-facing behavior changed
+    input:
+      - work/current.md
+      - work/artifacts/<feature_id>/implementer.md
+      - work/artifacts/<feature_id>/reviewer.json
+      - work/artifacts/<feature_id>/security.json
+      - work/artifacts/<feature_id>/qa.json
+    output:
+      - work/artifacts/<feature_id>/documenter.md
+
   - name: close
     owner: leader
     required: true
+    input:
+      - work/current.md
+      - work/artifacts/<feature_id>/implementer.md
+      - work/artifacts/<feature_id>/reviewer.json
+      - work/artifacts/<feature_id>/security.json
+      - work/artifacts/<feature_id>/qa.json
+      - work/artifacts/<feature_id>/documenter.md
     output:
       - work/artifacts/<feature_id>/leader-close.json
       - work/history.md
+    post_actions:
+      - scripts/close_feature.py <feature_id>
 
 close_requirements:
   - reviewer.json.verdict == "APPROVED"