feat(kotlin): add x402 exact client

.github/workflows/ci.yml

@@ -230,12 +230,12 @@ jobs:
         with:
           name: html-assets
       - name: Install Surfnet helper dependencies
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
       - name: Start Surfnet
         working-directory: .
         run: |
-          node tests/interop/start-surfnet-proxy.mjs &
+          node harness/start-surfnet-proxy.mjs &
           ready=0
           for i in $(seq 1 50); do
             if curl -sf -X POST http://localhost:8899 \
@@ -270,12 +270,12 @@ jobs:
         with:
           name: html-assets
       - name: Install Surfnet helper dependencies
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
       - name: Start Surfnet
         working-directory: .
         run: |
-          node tests/interop/start-surfnet-proxy.mjs &
+          node harness/start-surfnet-proxy.mjs &
           ready=0
           for i in $(seq 1 50); do
             if curl -sf -X POST http://localhost:8899 \
@@ -344,12 +344,12 @@ jobs:
         with:
           name: html-assets
       - name: Install Surfnet helper dependencies
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
       - name: Start Surfnet
         working-directory: .
         run: |
-          node tests/interop/start-surfnet-proxy.mjs &
+          node harness/start-surfnet-proxy.mjs &
           ready=0
           for i in $(seq 1 50); do
             if curl -sf -X POST http://localhost:8899 \
@@ -419,42 +419,42 @@ jobs:
         working-directory: rust
         run: cargo build -p solana-mpp --bin interop_client --bin interop_server
       - name: Install interop harness
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: "3.3"
           bundler-cache: true
           working-directory: ruby
       - name: Typecheck interop harness
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm typecheck
       - name: Run Rust client interop smoke
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "rust client pays typescript server"
         env:
           MPP_INTEROP_CLIENTS: rust
           MPP_INTEROP_SERVERS: typescript
       - name: Run Rust server interop smoke
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "typescript client pays rust server"
         env:
           MPP_INTEROP_CLIENTS: typescript
           MPP_INTEROP_SERVERS: rust
       - name: Run Rust end-to-end interop smoke
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "rust client pays rust server"
         env:
           MPP_INTEROP_CLIENTS: rust
           MPP_INTEROP_SERVERS: rust
       - name: Run Ruby server interop smoke
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "typescript client pays ruby server"
         env:
           MPP_INTEROP_CLIENTS: typescript
           MPP_INTEROP_SERVERS: ruby
       - name: Run Rust client to Ruby server interop smoke
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "rust client pays ruby server"
         env:
           MPP_INTEROP_CLIENTS: rust

.github/workflows/lua.yml

@@ -142,19 +142,19 @@ jobs:
         run: cargo build --bin interop_client
 
       - name: Install interop harness deps
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
 
       - name: TS-to-Lua focused matrix
-        working-directory: tests/interop
+        working-directory: harness
         env:
           MPP_INTEROP_CLIENTS: typescript
           MPP_INTEROP_SERVERS: lua
           MPP_INTEROP_SCENARIOS: charge-basic,charge-split-ata,charge-network-mismatch,charge-cross-route-replay
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "typescript client pays lua server"
 
       - name: Rust-to-Lua focused matrix
-        working-directory: tests/interop
+        working-directory: harness
         env:
           MPP_INTEROP_CLIENTS: rust
           MPP_INTEROP_SERVERS: lua

.github/workflows/php.yml

@@ -70,23 +70,23 @@ jobs:
         working-directory: rust
         run: cargo build -p solana-mpp --bin interop_client
       - name: Install interop harness
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
       - name: Install PHP interop dependencies
         working-directory: php
         run: composer install --no-interaction --no-progress
       - name: Typecheck interop harness
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm typecheck
       - name: Run PHP server interop smoke
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "typescript client pays php server"
         env:
           MPP_INTEROP_CLIENTS: typescript
           MPP_INTEROP_SERVERS: php
           MPP_INTEROP_SCENARIOS: charge-basic,charge-split-ata,charge-network-mismatch,charge-cross-route-replay
       - name: Run Rust client PHP server interop smoke
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "rust client pays php server"
         env:
           MPP_INTEROP_CLIENTS: rust

.github/workflows/python.yml

@@ -77,7 +77,7 @@ jobs:
           python -m pip install --upgrade pip
           pip install -e ".[dev]"
       # Critical order: install + build the TypeScript workspace BEFORE
-      # installing the interop harness. tests/interop has
+      # installing the interop harness. harness has
       # ``"@solana/mpp": "file:../../typescript/packages/mpp"`` which
       # pnpm copies into node_modules at install time. If the typescript
       # package has no dist/ at that moment, the TS interop client crashes
@@ -95,16 +95,16 @@ jobs:
         working-directory: rust
         run: cargo build --bin interop_client --bin interop_server
       - name: Install interop harness
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
       - name: Focused TS-to-Python interop
-        working-directory: tests/interop
+        working-directory: harness
         env:
           MPP_INTEROP_CLIENTS: typescript
           MPP_INTEROP_SERVERS: python
         run: pnpm exec vitest run test/e2e.test.ts
       - name: Focused Rust-to-Python interop
-        working-directory: tests/interop
+        working-directory: harness
         env:
           MPP_INTEROP_CLIENTS: rust
           MPP_INTEROP_SERVERS: python

.github/workflows/swift.yml

@@ -44,25 +44,25 @@ jobs:
         working-directory: typescript
         run: pnpm --filter @solana/mpp build
       - name: Install interop harness
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm install --frozen-lockfile
       - name: Build Swift interop client
-        working-directory: tests/interop/swift-client
+        working-directory: harness/swift-client
         run: swift build
       - name: Build Rust interop server
         working-directory: rust
         run: cargo build --bin interop_server
       - name: Typecheck interop harness
-        working-directory: tests/interop
+        working-directory: harness
         run: pnpm typecheck
       - name: Run Swift client interop smoke against TypeScript server
-        working-directory: tests/interop
+        working-directory: harness
         env:
           MPP_INTEROP_CLIENTS: swift
           MPP_INTEROP_SERVERS: typescript
         run: pnpm exec vitest run test/e2e.test.ts --testNamePattern "swift client pays typescript server"
       - name: Run Swift client interop smoke against Rust server
-        working-directory: tests/interop
+        working-directory: harness
         env:
           MPP_INTEROP_CLIENTS: swift
           MPP_INTEROP_SERVERS: rust

.gitignore

@@ -28,9 +28,11 @@ __pycache__/
 .coverage
 .venv/
 *.pyc
-tests/interop/go-client/go-client
+harness/go-client/go-client
 .claude/
 .gocache
 mpp-sdk-self-learning/
 .build/
 go/coverage.out
+notes/codex-review/
+notes/codex-review-*.md

README.md

@@ -62,9 +62,9 @@ The interop harness can run a full client/server cross-product, but CI keeps the
 | Python | ![Python](https://img.shields.io/badge/coverage-87%25-green) | `just py-test` |
 | Lua | ![Lua](https://img.shields.io/badge/coverage-41_tests-blue) | `just lua-test` |
 | Ruby | ![Ruby](https://img.shields.io/badge/coverage-98%25-green) | `just rb-test-cover` |
-| Interop | ![Interop](https://img.shields.io/badge/interop-TypeScript_harness-brightgreen) | `cd tests/interop && pnpm test` |
+| Interop | ![Interop](https://img.shields.io/badge/interop-TypeScript_harness-brightgreen) | `cd harness && pnpm test` |
 
-See [`tests/interop/README.md`](tests/interop/README.md) for the process adapter contract used by the Surfpool-backed client/server matrix.
+See [`harness/README.md`](harness/README.md) for the process adapter contract used by the Surfpool-backed client/server matrix.
 
 ## Install
 

docs/security/compute-budget-caps.md

@@ -53,7 +53,7 @@ this monorepo.
 | Go (#101)   | `go/server/server.go` (`maxComputeUnitLimit`)              | pending PR #101 merge                     |
 | Python (#106) | `python/src/solana_mpp/server/mpp.py`                    | pending PR #106 merge                     |
 
-`tests/interop/test/compute-budget-caps.test.ts` parses each file above
+`harness/test/compute-budget-caps.test.ts` parses each file above
 and asserts byte-identical literals against the canonical pair. Go and
 Python rows are marked `optional: true` until their PRs land, then
 flip to required and surface drift the same way as the other SDKs.
@@ -66,8 +66,8 @@ flip to required and surface drift the same way as the other SDKs.
    code when either limit is exceeded; include the cap value in the
    reason string for parity with the existing SDKs.
 3. Append a row to `SDKS` in
-   `tests/interop/test/compute-budget-caps.test.ts` and to the table
+   `harness/test/compute-budget-caps.test.ts` and to the table
    above. Append a fixture row to
    `charge-compute-budget-over-cap` in
-   `tests/interop/src/intents/charge.ts` once the SDK is wired into the
+   `harness/src/intents/charge.ts` once the SDK is wired into the
    interop harness.

go/README.md

@@ -128,7 +128,7 @@ localnet fixture.
 ## Running the interop adapters
 
 ```bash
-cd tests/interop/go-server
+cd harness/go-server
 go run .   # starts a Surfpool-backed protected endpoint on a random port
 
 cd ../go-client
@@ -193,7 +193,7 @@ same structural transaction verifier as pull mode, consumes the
 signature through replay storage, and emits the same receipt shape.
 
 The direct Go interop server at
-[`tests/interop/go-server/main.go`](../tests/interop/go-server/main.go)
+[`harness/go-server/main.go`](../harness/go-server/main.go)
 exercises this end-to-end through Surfpool for both TypeScript and Rust
 clients.
 
@@ -258,15 +258,15 @@ The CI Go job runs the SDK packages with `-coverprofile` and enforces a
 
 ## Interop
 
-The cross-language interop harness lives in `../tests/interop`. The Go
-SDK ships both a client (`tests/interop/go-client`) and a server
-(`tests/interop/go-server`) adapter. Both are opt-in via the
+The cross-language interop harness lives in `../harness`. The Go
+SDK ships both a client (`harness/go-client`) and a server
+(`harness/go-server`) adapter. Both are opt-in via the
 `MPP_INTEROP_CLIENTS` and `MPP_INTEROP_SERVERS` env vars.
 
 Focused harness commands:
 
 ```bash
-cd tests/interop
+cd harness
 MPP_INTEROP_CLIENTS=go         MPP_INTEROP_SERVERS=rust pnpm test
 MPP_INTEROP_CLIENTS=typescript MPP_INTEROP_SERVERS=go   pnpm test
 MPP_INTEROP_CLIENTS=rust       MPP_INTEROP_SERVERS=go   pnpm test

go/mpp.go

@@ -8,7 +8,7 @@
 // transaction builders live in the `client` subpackage. The wire format
 // and module split mirror the Rust reference crate documented in
 // skills/pay-sdk-implementation; cross-language behavior is locked via
-// the interop harness at tests/interop.
+// the interop harness at harness.
 package mpp
 
 import (

kotlin/.gitignore

@@ -0,0 +1,6 @@
+.gradle/
+build/
+!gradle-wrapper.jar
+local.properties
+*.iml
+.idea/