feat(specs): add diagnostic extension for payment failure signaling

.github/workflows/publish_npm_scoped_x402_fastify.yml

@@ -0,0 +1,56 @@
+name: Publish @x402/fastify package to NPM
+
+on:
+  workflow_dispatch:
+
+jobs:
+  publish-npm-x402-fastify:
+    runs-on: ubuntu-latest
+    environment: ${{ github.ref == 'refs/heads/main' && 'npm' || '' }}
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@41ff72655975bd51cab0327fa583b6e92b6d3061
+        with:
+          version: 10.7.0
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "24"
+          registry-url: "https://registry.npmjs.org"
+          cache: "pnpm"
+          cache-dependency-path: ./typescript
+
+      - name: Update npm for OIDC trusted publishing
+        run: npm install -g npm@latest
+
+      - name: Configure npm for trusted publishing
+        run: npm config delete always-auth 2>/dev/null || true
+
+      - name: Install and build
+        working-directory: ./typescript
+        run: |
+          pnpm install --frozen-lockfile
+          pnpm -r --filter=@x402/core --filter=@x402/extensions --filter=@x402/fastify run build
+
+      - name: Publish @x402/fastify package
+        working-directory: ./typescript/packages/http/fastify
+        run: |
+          # Get package information directly
+          PACKAGE_NAME=$(node -p "require('./package.json').name")
+          PACKAGE_VERSION=$(node -p "require('./package.json').version")
+
+          echo "Package: $PACKAGE_NAME@$PACKAGE_VERSION"
+
+          # Check if running on main branch
+          if [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
+            echo "Publishing to NPM (main branch)"
+            pnpm publish --provenance --access public
+          else
+            echo "Dry run only (non-main branch: ${{ github.ref }})"
+            pnpm publish --dry-run --no-git-checks
+          fi

.github/workflows/publish_npm_scoped_x402_stellar.yml

@@ -0,0 +1,56 @@
+name: Publish @x402/stellar package to NPM
+
+on:
+  workflow_dispatch:
+
+jobs:
+  publish-npm-x402-stellar:
+    runs-on: ubuntu-latest
+    environment: ${{ github.ref == 'refs/heads/main' && 'npm' || '' }}
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@41ff72655975bd51cab0327fa583b6e92b6d3061
+        with:
+          version: 10.7.0
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "24"
+          registry-url: "https://registry.npmjs.org"
+          cache: "pnpm"
+          cache-dependency-path: ./typescript
+
+      - name: Update npm for OIDC trusted publishing
+        run: npm install -g npm@latest
+
+      - name: Configure npm for trusted publishing
+        run: npm config delete always-auth 2>/dev/null || true
+
+      - name: Install and build
+        working-directory: ./typescript
+        run: |
+          pnpm install --frozen-lockfile
+          pnpm -r --filter=@x402/core --filter=@x402/stellar run build
+
+      - name: Publish @x402/stellar package
+        working-directory: ./typescript/packages/mechanisms/stellar
+        run: |
+          # Get package information directly
+          PACKAGE_NAME=$(node -p "require('./package.json').name")
+          PACKAGE_VERSION=$(node -p "require('./package.json').version")
+
+          echo "Package: $PACKAGE_NAME@$PACKAGE_VERSION"
+
+          # Check if running on main branch
+          if [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
+            echo "Publishing to NPM (main branch)"
+            pnpm publish --provenance --access public
+          else
+            echo "Dry run only (non-main branch: ${{ github.ref }})"
+            pnpm publish --dry-run --no-git-checks
+          fi

.gitignore

@@ -1,4 +1,5 @@
 .env
+.env.local
 node_modules/
 dist/
 .turbo/
@@ -20,12 +21,17 @@ e2e/clients/mcp-go/mcp-client
 e2e/clients/mcp-go/mcp-go
 e2e/facilitators/go/facilitator
 e2e/facilitators/go/go
+e2e/servers/echo/echo
 e2e/servers/gin/gin
 e2e/servers/gin/server
+e2e/servers/nethttp/nethttp
 e2e/servers/mcp-go/mcp-go
 e2e/servers/mcp-go/mcp-server
 e2e/legacy/servers/gin/gin
 
+# Example build artifacts
+examples/go/servers/upto/upto
+
 # Agent artifacts
 TASK.md
 .claude/

CONTRIBUTING.md

@@ -135,6 +135,18 @@ x402 aims to be chain-agnostic. New chain implementations are welcome.
 
 Because different chains have different best practices, a scheme may have a different mechanism on a new chain than it does on EVM. If the scheme mechanism varies from the reference implementation, the x402 Foundation will re-audit the scheme for that chain before accepting.
 
+### Adding a Default Asset for an EVM Chain
+
+If your chain is EVM-compatible and you want to add a default stablecoin for
+dollar-string pricing (`"$0.10"`), you don't need the full 3-PR workflow below. See:
+
+- [Go: DEFAULT_ASSET.md](go/mechanisms/evm/DEFAULT_ASSET.md)
+- [TypeScript: DEFAULT_ASSET.md](typescript/packages/mechanisms/evm/src/exact/server/DEFAULT_ASSET.md)
+
+These guides include a cross-SDK checklist of every file to update.
+
+### Adding a New Chain Family
+
 ### PR 1: Specification Only
 
 Open a PR with specs for one payment scheme implementation.

README.md

@@ -51,9 +51,9 @@ go get github.com/coinbase/x402/go
 - **Open standard:** x402 is an open standard, freely accessible and usable by anyone. It will never force reliance on a single party.
 - **HTTP / Transport Native:** x402 is meant to seamlessly complement existing data transportation. It should whenever possible not mandate additional requests outside the scope of a typical client / server flow.
 - **Network, token, and currency agnostic:** we welcome contributions that add support for new networks (both crypto and fiat), signing standards, or schemes, so long as they meet our acceptance criteria laid out in [CONTRIBUTING.md](https://github.com/coinbase/x402/blob/main/CONTRIBUTING.md). x402 may extend support to fiat based networks, but will never deprioritize onchain payments in favor of fiat payments.
-- **Backwards Compatible:** x402 will not deprecate support for any existing networks unless such removal is deemed necessary for the security of the standard
+- **Backwards Compatible:** x402 will not deprecate support for any existing networks unless such removal is deemed necessary for the security of the standard. Whenever possible, x402 will aim for backwards compatibility for non-major version changes.
 - **Trust minimizing:** all payment schemes must not allow for the facilitator or resource server to move funds, other than in accordance with client intentions
-- **Easy to use:** x402 needs to be 10x better than existing ways to pay on the internet. This means abstracting as many details of crypto as possible away from the client and resource server, and into the facilitator. This means the client/server should not need to think about gas, rpc, etc.
+- **Easy to use:** It is the goal of the x402 community to improve ease of use relative to other forms of payment on the Internet. This means abstracting as many details of crypto as possible away from the client and resource server, and into the facilitator. This means the client/server should not need to think about gas, rpc, etc.
 
 ## Ecosystem