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+# Shared Crate Strategy: WZP ↔ featherChat
+
+**Goal:** Both projects import each other's crates directly instead of duplicating code. A change to identity derivation in featherChat automatically applies in WZP, and vice versa for call signaling types.
+
+---
+
+## Current Problem
+
+- `warzone-protocol` uses workspace dependency inheritance (`Cargo.toml` has `ed25519-dalek.workspace = true`). When WZP tries to use it as a path dep, Cargo fails because it can't resolve workspace references from outside the featherChat workspace.
+- WZP had to mirror featherChat's `identity.rs`, `mnemonic.rs`, and `Fingerprint` type in `wzp-crypto/src/identity.rs` — duplicate code that can drift.
+- featherChat will need `wzp_proto::SignalMessage` for the `WireMessage::CallSignal` variant — another potential duplication.
+
+## Solution: Make Key Crates Standalone-Importable
+
+### What featherChat Needs to Do
+
+#### FC-CRATE-1: Make `warzone-protocol` standalone-publishable
+
+**File:** `warzone/crates/warzone-protocol/Cargo.toml`
+
+Replace all `workspace = true` references with explicit versions:
+
+```toml
+# Before:
+ed25519-dalek.workspace = true
+x25519-dalek.workspace = true
+
+# After:
+ed25519-dalek = { version = "2", features = ["serde", "rand_core"] }
+x25519-dalek = { version = "2", features = ["serde", "static_secrets"] }
+chacha20poly1305 = "0.10"
+hkdf = "0.12"
+sha2 = "0.10"
+rand = "0.8"
+bip39 = "2"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+bincode = "1"
+thiserror = "2"
+hex = "0.4"
+base64 = "0.22"
+uuid = { version = "1", features = ["v4"] }
+zeroize = { version = "1", features = ["derive"] }
+chrono = { version = "0.4", features = ["serde"] }
+k256 = { version = "0.13", features = ["ecdsa", "serde"] }
+tiny-keccak = { version = "2", features = ["keccak"] }
+```
+
+**Keep workspace inheritance working too** by using the `[package]` fallback pattern:
+```toml
+[package]
+name = "warzone-protocol"
+version = "0.0.20"
+edition = "2021"
+# Remove version.workspace and edition.workspace — use explicit values
+```
+
+This way the crate still works inside the featherChat workspace AND can be imported by WZP as a path dependency.
+
+**Test:** From the WZP repo, this should work:
+```toml
+# In wzp-crypto/Cargo.toml:
+warzone-protocol = { path = "../../deps/featherchat/warzone/crates/warzone-protocol" }
+```
+
+**Effort:** 30 minutes. Mechanical replacement, then `cargo build` to verify.
+
+#### FC-CRATE-2: Add `wzp-proto` as a git dependency for `CallSignal`
+
+**File:** `warzone/crates/warzone-protocol/Cargo.toml`
+
+```toml
+[dependencies]
+# WarzonePhone signaling types (for CallSignal WireMessage variant)
+wzp-proto = { git = "ssh://git@git.manko.yoga:222/manawenuz/wz-phone.git", optional = true }
+
+[features]
+default = []
+wzp = ["wzp-proto"]
+```
+
+**File:** `warzone/crates/warzone-protocol/src/message.rs`
+
+```rust
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub enum WireMessage {
+    // ... existing variants ...
+
+    /// Voice/video call signaling (requires "wzp" feature).
+    #[cfg(feature = "wzp")]
+    CallSignal {
+        id: String,
+        sender_fingerprint: String,
+        signal: wzp_proto::SignalMessage,  // Typed, not opaque bytes
+    },
+
+    /// Voice/video call signaling (without wzp feature — opaque bytes).
+    #[cfg(not(feature = "wzp"))]
+    CallSignal {
+        id: String,
+        sender_fingerprint: String,
+        signal: Vec<u8>,  // Opaque JSON bytes
+    },
+}
+```
+
+**Alternative (simpler):** Always use `Vec<u8>` for the signal field and let the consumer deserialize. This avoids the feature flag complexity:
+
+```rust
+CallSignal {
+    id: String,
+    sender_fingerprint: String,
+    signal_json: String,  // JSON-serialized wzp_proto::SignalMessage
+},
+```
+
+featherChat server treats it as opaque. WZP client deserializes it to `SignalMessage`.
+
+**Effort:** 1-2 hours.
+
+#### FC-CRATE-3: Extract shared identity types to a micro-crate (optional, long-term)
+
+Create `warzone-identity` crate containing only:
+- `Seed` (generation, from_bytes, from_hex, from_mnemonic, to_mnemonic)
+- `IdentityKeyPair` (derive from seed)
+- `PublicIdentity` (verifying key, encryption key, fingerprint)
+- `Fingerprint` (SHA-256 truncated, display format)
+- `hkdf_derive()` helper
+
+Both `warzone-protocol` and `wzp-crypto` depend on `warzone-identity` instead of each implementing their own. This is the cleanest long-term solution but requires more refactoring.
+
+**Crate structure:**
+```
+warzone-identity/
+├── Cargo.toml  (standalone, no workspace inheritance)
+├── src/
+│   ├── lib.rs
+│   ├── seed.rs
+│   ├── identity.rs
+│   ├── fingerprint.rs
+│   └── mnemonic.rs
+```
+
+**Dependencies:** ed25519-dalek, x25519-dalek, hkdf, sha2, bip39, hex, zeroize
+
+Both projects import it:
+```toml
+# featherChat:
+warzone-identity = { path = "../warzone-identity" }
+
+# WZP (via submodule):
+warzone-identity = { path = "deps/featherchat/warzone-identity" }
+```
+
+**Effort:** Half a day. Extract code from warzone-protocol, update imports in both projects.
+
+---
+
+### What WZP Needs to Do (after featherChat completes FC-CRATE-1)
+
+#### WZP-CRATE-1: Replace identity mirror with real dependency
+
+Once `warzone-protocol` is standalone-importable:
+
+**File:** `crates/wzp-crypto/Cargo.toml`
+```toml
+# Remove bip39 and hex (now comes from warzone-protocol)
+# Add:
+warzone-protocol = { path = "../../deps/featherchat/warzone/crates/warzone-protocol" }
+```
+
+**File:** `crates/wzp-crypto/src/identity.rs`
+Replace the entire file with re-exports:
+```rust
+//! featherChat identity — re-exported from warzone-protocol.
+pub use warzone_protocol::identity::{IdentityKeyPair, Seed};
+pub use warzone_protocol::types::Fingerprint;
+```
+
+**File:** `crates/wzp-crypto/src/handshake.rs`
+Use `warzone_protocol::identity::Seed` internally instead of raw HKDF calls.
+
+**Effort:** 1 hour (after FC-CRATE-1 is done).
+
+#### WZP-CRATE-2: Make `wzp-proto` standalone-importable
+
+`wzp-proto` already has explicit dependency versions (not workspace-inherited for external deps). It should work as a git dependency from featherChat. Verify:
+
+```bash
+# From a scratch project:
+cargo add --git ssh://git@git.manko.yoga:222/manawenuz/wz-phone.git wzp-proto
+```
+
+If this fails, replace any remaining workspace references in `wzp-proto/Cargo.toml` with explicit versions.
+
+**Key types featherChat needs from wzp-proto:**
+- `SignalMessage` (CallOffer, CallAnswer, IceCandidate, Hangup, etc.)
+- `QualityProfile` (for codec negotiation)
+- `HangupReason`
+
+**Effort:** 30 minutes to verify and fix.
+
+---
+
+## Recommended Order
+
+1. **FC-CRATE-1** — Make warzone-protocol standalone (30 min, unblocks everything)
+2. **WZP-CRATE-2** — Verify wzp-proto works as git dep (30 min)
+3. **FC-CRATE-2** — Add CallSignal with opaque signal_json field (1-2 hours)
+4. **WZP-CRATE-1** — Replace identity mirror with real dep (1 hour)
+5. **FC-CRATE-3** — Extract warzone-identity micro-crate (optional, half day)
+
+After steps 1-4, both projects share types directly:
+- WZP imports `warzone-protocol` for identity/seed/fingerprint
+- featherChat imports `wzp-proto` (via git) for `SignalMessage` types
+- No duplicated code, no drift risk
+
+---
+
+## Dependency Graph After Integration
+
+```
+warzone-identity (shared micro-crate, optional step 5)
+    ↑                    ↑
+warzone-protocol         wzp-crypto
+    ↑                    ↑
+warzone-server      wzp-proto ← wzp-codec, wzp-fec, wzp-transport
+    ↑                    ↑
+warzone-client      wzp-client, wzp-relay, wzp-web
+```