chore: add grpc spec

docs/specs/grpc/context.json

@@ -0,0 +1,92 @@
+{
+  "product_vision": {
+    "phase_1_goal": "Build a 3-node distributed Redis-compatible KV store with Raft consensus",
+    "networking_requirements": {
+      "protocol": "gRPC on port 7379 for internal Raft RPC between nodes",
+      "success_criteria": [
+        "Leader election <2s",
+        "11 chaos tests passing",
+        ">5,000 ops/sec performance"
+      ]
+    }
+  },
+  "existing_features": [
+    {
+      "name": "openraft-migration",
+      "status": "In Design",
+      "relevance": "Phase 4 includes Network Stub Implementation - gRPC will replace StubNetwork"
+    },
+    {
+      "name": "resp-protocol",
+      "status": "Complete (100%, 487 tests)",
+      "relevance": "Handles client-facing Redis protocol, separate from internal gRPC"
+    },
+    {
+      "name": "kv-service",
+      "status": "Specified, not started",
+      "relevance": "Will use raft crate for consensus operations"
+    }
+  ],
+  "architecture": {
+    "raft_crate_role": "Consensus + Transport Layer - wraps openraft with gRPC server/client",
+    "grpc_integration": {
+      "description": "Implements RaftNetwork trait for inter-node communication",
+      "location": "crates/raft/, protos in crates/raft/proto/",
+      "replaces": "StubNetwork placeholder with OpenRaftNetwork implementation",
+      "trait": "openraft::RaftNetwork<RaftTypeConfig>",
+      "server_port": 7379,
+      "rpc_types": ["RequestVote", "AppendEntries", "InstallSnapshot"]
+    },
+    "dependencies": {
+      "upstream": ["storage crate", "common crate"],
+      "downstream": ["kv service", "seshat binary"],
+      "external": [
+        "openraft 0.10+",
+        "tonic 0.11+",
+        "prost 0.14+ (MUST match tonic version)"
+      ]
+    }
+  },
+  "standards": {
+    "tech_stack": {
+      "rust_version": "1.90+",
+      "async_runtime": "tokio",
+      "grpc": "tonic 0.11+ / prost 0.14+",
+      "serialization": "Protocol Buffers",
+      "errors": "thiserror",
+      "logging": "tracing"
+    },
+    "key_requirements": [
+      "5s connection/request timeout",
+      "TDD workflow mandatory",
+      "Single prost version (0.14) - CRITICAL for compatibility",
+      "Async-first design"
+    ],
+    "testing_approach": {
+      "unit": "protobuf serialization, client/server logic",
+      "integration": "2-node message exchange",
+      "chaos": "11 scenarios (network partitions, failures)"
+    }
+  },
+  "implementation_guidance": {
+    "relationship_to_openraft": "OpenRaft migration defines StubNetwork placeholder, gRPC spec replaces stub with full tonic/prost implementation",
+    "key_design_decisions": [
+      "Connection pooling with HashMap<NodeId, GrpcClient>",
+      "Retry logic with exponential backoff (max 3 attempts)",
+      "DNS-based peer discovery (hostname:port)",
+      "Comprehensive error mapping (tonic::Status → RaftError)"
+    ],
+    "file_organization": {
+      "proto_files": "crates/raft/proto/*.proto",
+      "server": "crates/raft/src/grpc_server.rs",
+      "client": "crates/raft/src/grpc_client.rs",
+      "network": "crates/raft/src/network.rs (replaces network_stub.rs)"
+    }
+  },
+  "reference_documents": [
+    "docs/specs/openraft/design.md - OpenRaft migration design",
+    "docs/standards/tech.md - gRPC standards",
+    "docs/architecture/crates.md - Raft crate architecture"
+  ],
+  "next_steps": "Ready for /spec:design grpc to generate technical design"
+}