Add Phase C2 charter (planning-only, no implementation)

Author: iamfurydammit

PHASE-C2-CHARTER.md

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+PHASE-C2-CHARTER.md
+Project: XSTRP (XRP Safe Transfer & Recovery Protocol)
+Phase: C2 — Interface & Integration Planning
+1. Phase Status
+
+Phase C2 is ACTIVE (Planning-Only)
+Phase C1 remains COMPLETE, FROZEN, and IMMUTABLE.
+
+No Phase C1 artifacts may be modified, reinterpreted, or superseded.
+
+2. Phase Purpose
+
+The sole purpose of Phase C2 is to define safe, explicit extension boundaries around the frozen XSTRP core.
+
+Phase C2 exists to answer how XSTRP could be connected to external systems without:
+
+altering protocol logic,
+
+weakening safety guarantees, or
+
+introducing enforcement assumptions.
+
+This phase prepares interfaces, not implementations.
+
+3. Scope of Allowed Work
+
+Phase C2 MAY include:
+
+📄 Documentation
+
+Interface descriptions
+
+Integration scenarios (non-binding)
+
+Architectural diagrams (non-normative)
+
+🧩 Rust trait definitions only
+
+No logic
+
+No state mutation
+
+No side effects
+
+🧪 Compile-time checks
+
+Trait bounds
+
+Type-level constraints
+
+📝 Threat-surface analysis for hypothetical integrations
+
+All changes must be additive.
+
+4. Explicit Non-Goals
+
+Phase C2 MUST NOT include:
+
+❌ Any modification to RFC-XSTRP-0001
+
+❌ Any modification to Phase C1 Rust code
+
+❌ XRPL integration of any kind
+
+❌ Cryptographic primitives or signing
+
+❌ Networking, transport, or messaging layers
+
+❌ Persistence or storage implementations
+
+❌ Enforcement of IntentBinding
+
+❌ Runtime logic, handlers, or adapters
+
+❌ “Just a stub” implementations
+
+If logic executes, Phase C2 has been violated.
+
+5. Interface Philosophy
+
+All Phase C2 interfaces must be:
+
+Purely declarative
+
+Opt-in
+
+Externally supplied
+
+Protocol-agnostic
+
+Non-authoritative
+
+XSTRP core remains the only source of truth for intent state transitions.
+
+6. Safety Invariants (Inherited from Phase C1)
+
+Phase C2 must not introduce any mechanism that:
+
+Enables fund release without receiver participation
+
+Enables sender redirection after intent creation
+
+Allows third-party seizure or coercion
+
+Creates a stranded-fund state
+
+Weakens deterministic state transitions
+
+If an interface could violate these, it must be rejected or redesigned.
+
+7. Exit Criteria
+
+Phase C2 may be considered complete when:
+
+All intended interfaces are documented
+
+All Rust traits compile
+
+No runtime logic exists
+
+No Phase C1 files were altered
+
+A new freeze declaration is written (PHASE-C2-FROZEN.md)
+
+8. Freeze Conditions
+
+Phase C2 MUST be frozen immediately if:
+
+Implementation pressure appears
+
+External systems begin dictating design
+
+Safety invariants are questioned
+
+Scope creep occurs
+
+The beginner-pace constraint is threatened
+
+Freeze is always preferred over progress.
+
+9. Developer Constraints (Still Enforced)
+
+Beginner pace
+
+Safety > features
+
+Additive changes only
+
+Explicit phase boundaries
+
+No silent scope creep
+
+No urgency bias
+
+10. Authority
+
+This charter governs all Phase C2 work.
+Any deviation requires an explicit, written amendment before action.
+
+Phase C2 Charter — Adopted
+Status: ACTIVE (Planning-Only)