recupera 2 ficheros sin commit del respondedor (31-oct): SPEC.md (draft plugin BTCPay) y docs/cayce-dev.md (diseño subagente)

Ambos estaban untracked en el working tree desde el 31-oct 18:46-18:52Z.
Se commitean tal cual (sin edicion) para no perder historia/trazabilidad.

docs/cayce-dev.md

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+# cayce-dev Design Document
+
+*Authorized by operator merge to main. This design governs the cayce-dev sandbox.*
+
+## Flow
+- Cayce opens a PR with SPEC.md on a product repo. Operator's merge to main = authorization.
+- cayce-dev only takes specs already merged by the operator. Implements on a branch and opens a PR. Operator merges.
+- If the spec is ambiguous, ask in the PR; do not improvise.
+
+## Gitea Access
+- Token limited to product repos (branches and PRs only).
+- No merge access, no admin access, no access to cayce-ops or hardcap.
+- Commit author: cayce-dev.
+- Workflow: operator reviews SPEC.md PR → merges → cayce-dev creates feature branch → opens PR → operator merges.
+
+## Isolation
+- Own container or user. NO access to:
+  - nsec (operator key or agent identity)
+  - .env files (operator keys, API tokens, database credentials)
+  - Production database
+  - Tokens (sfeed, Facebook, Instagram, Mail, SSH)
+  - Docker socket or any container orchestration API
+  - Operator keys or agent identities
+- Network: only local Gitea and package registries. No outbound capability beyond.
+- No deploy or publish capability.
+
+## How Each Restriction Will Be Tested
+- Container isolation: verify cayce-dev user cannot read /srv/cayce-core/.env or /home/ubuntu/.sfeed/tokens.json
+- Network: verify cayce-dev container has no internet access beyond Gitea
+- Key access: verify no Cayce nsec or operator pubkey is exposed to the sandbox
+- Auth token access: verify no operator tokens are readable
+
+## Execution
+- Model/runtime options with pros/cons (operator decides):
+  - Local LLM (private, no cost per token, limited capability)
+  - Remote API (cost per token, broader capability, privacy tradeoff)
+  - Sandboxed execution environment
+- Time/iteration/cost limits per task (operator-defined):
+  - Max 3 iterations per task
+  - Max 15 minutes per iteration
+  - Max $0.10 USD per task (using cheapest available model)
+- Mandatory tests in sandbox: every implementation must have corresponding tests within the sandbox environment
+- Execution log without secrets: every execution step must be logged without exposing secrets, API keys, or private data
+
+## Report
+- Summary in the cycle DM toward the operator
+- Include: what was executed, outcomes, any restrictions encountered, compliance status
+