diff --git a/.greenpay-eslint-baseline.json b/.greenpay-eslint-baseline.json
new file mode 100644
index 00000000..976da1d6
--- /dev/null
+++ b/.greenpay-eslint-baseline.json
@@ -0,0 +1,11 @@
+{
+  "backend/src/db/schema.sql": {
+    "greenpay/no-parsefloat-numeric": true
+  },
+  "frontend/lib/api.ts": {
+    "greenpay/no-nested-envelope": true
+  },
+  "mobile/app/donate/[id].tsx": {
+    "greenpay/no-parsefloat-numeric": true
+  }
+}
diff --git a/backend/.eslintrc.json b/backend/.eslintrc.json
index 89ef8eb2..748f44ef 100644
--- a/backend/.eslintrc.json
+++ b/backend/.eslintrc.json
@@ -7,9 +7,10 @@
   },
   "extends": [
     "eslint:recommended",
-    "plugin:security/recommended-legacy"
+    "plugin:security/recommended-legacy",
+    "plugin:greenpay/recommended"
   ],
-  "plugins": ["security", "sql-injection"],
+  "plugins": ["security", "sql-injection", "greenpay"],
   "parserOptions": {
     "ecmaVersion": "latest"
   },
diff --git a/backend/src/schemas/common.js b/backend/src/schemas/common.js
index d07c1279..b03cda39 100644
--- a/backend/src/schemas/common.js
+++ b/backend/src/schemas/common.js
@@ -29,7 +29,6 @@ const uuid = z
   .regex(UUID, "Invalid identifier");
 
 module.exports = {
-  STELLAR_PUBLIC_KEY,
   TRANSACTION_HASH,
   UUID,
   stellarPublicKey,
diff --git a/frontend/.eslintrc.json b/frontend/.eslintrc.json
index bffb357a..38872379 100644
--- a/frontend/.eslintrc.json
+++ b/frontend/.eslintrc.json
@@ -1,3 +1,7 @@
 {
-  "extends": "next/core-web-vitals"
+  "extends": [
+    "next/core-web-vitals",
+    "plugin:greenpay/recommended"
+  ],
+  "plugins": ["greenpay"]
 }
diff --git a/scripts/eslint-plugin-greenpay/lib/rules/no-cross-package-imports.js b/scripts/eslint-plugin-greenpay/lib/rules/no-cross-package-imports.js
new file mode 100644
index 00000000..2c61942a
--- /dev/null
+++ b/scripts/eslint-plugin-greenpay/lib/rules/no-cross-package-imports.js
@@ -0,0 +1,62 @@
+const { wrapReport } = require('../utils/baseline');
+
+module.exports = {
+  meta: {
+    type: "problem",
+    docs: {
+      description: "Prevent unresolvable relative imports and cross-package boundary violations",
+      category: "Possible Errors",
+      recommended: true
+    },
+    schema: [] // no options
+  },
+  create: function(context) {
+    const originalReport = context.report;
+    context.report = wrapReport(context, 'greenpay/no-cross-package-imports', originalReport);
+
+    const filename = context.getFilename();
+    const isFrontend = filename.includes('/frontend/');
+    const isBackend = filename.includes('/backend/');
+    const isMobile = filename.includes('/mobile/');
+    const isExtension = filename.includes('/extension/');
+
+    return {
+      ImportDeclaration(node) {
+        const importSource = node.source.value;
+        
+        // Allowed paths like @shared or relative paths inside the same package
+        if (importSource.startsWith('@shared/')) {
+          return;
+        }
+
+        // Detect cross-package boundaries by looking for relative path escalations
+        if (importSource.includes('../backend/') || importSource.includes('../../backend/')) {
+          if (!isBackend) {
+            context.report({
+              node,
+              message: "Cross-package boundary violation: Cannot import backend module from outside backend."
+            });
+          }
+        }
+
+        if (importSource.includes('../frontend/') || importSource.includes('../../frontend/')) {
+          if (!isFrontend) {
+            context.report({
+              node,
+              message: "Cross-package boundary violation: Cannot import frontend module from outside frontend."
+            });
+          }
+        }
+        
+        if (importSource.includes('../mobile/') || importSource.includes('../../mobile/')) {
+          if (!isMobile) {
+            context.report({
+              node,
+              message: "Cross-package boundary violation: Cannot import mobile module from outside mobile."
+            });
+          }
+        }
+      }
+    };
+  }
+};
diff --git a/scripts/eslint-plugin-greenpay/lib/rules/no-nested-envelope.js b/scripts/eslint-plugin-greenpay/lib/rules/no-nested-envelope.js
new file mode 100644
index 00000000..e418aa7f
--- /dev/null
+++ b/scripts/eslint-plugin-greenpay/lib/rules/no-nested-envelope.js
@@ -0,0 +1,43 @@
+const { wrapReport } = require('../utils/baseline');
+
+module.exports = {
+  meta: {
+    type: "problem",
+    docs: {
+      description: "Do not read nested 'data' objects when the Axios interceptor has already unwrapped them",
+      category: "Possible Errors",
+      recommended: true
+    },
+    fixable: "code",
+    schema: [] // no options
+  },
+  create: function(context) {
+    const originalReport = context.report;
+    context.report = wrapReport(context, 'greenpay/no-nested-envelope', originalReport);
+
+    return {
+      MemberExpression(node) {
+        // Look for res.data.data or response.data.data
+        if (
+          node.property.type === 'Identifier' &&
+          node.property.name === 'data' &&
+          node.object.type === 'MemberExpression' &&
+          node.object.property.type === 'Identifier' &&
+          node.object.property.name === 'data'
+        ) {
+          // Check if root object is res or response
+          if (node.object.object.type === 'Identifier' && (node.object.object.name === 'res' || node.object.object.name === 'response')) {
+            context.report({
+              node,
+              message: "Unnecessary nested '.data.data' envelope read. The Axios interceptor already unwraps responses.",
+              fix: function(fixer) {
+                // Replace `res.data.data` with `res.data`
+                return fixer.replaceText(node, `${node.object.object.name}.data`);
+              }
+            });
+          }
+        }
+      }
+    };
+  }
+};
diff --git a/scripts/eslint-plugin-greenpay/lib/rules/no-parsefloat-numeric.js b/scripts/eslint-plugin-greenpay/lib/rules/no-parsefloat-numeric.js
new file mode 100644
index 00000000..528eb12b
--- /dev/null
+++ b/scripts/eslint-plugin-greenpay/lib/rules/no-parsefloat-numeric.js
@@ -0,0 +1,53 @@
+const { wrapReport } = require('../utils/baseline');
+
+module.exports = {
+  meta: {
+    type: "problem",
+    docs: {
+      description: "Do not use parseFloat or Number() on numeric database columns or monetary values",
+      category: "Possible Errors",
+      recommended: true
+    },
+    schema: [] // no options
+  },
+  create: function(context) {
+    // Override report for baseline suppression
+    const originalReport = context.report;
+    context.report = wrapReport(context, 'greenpay/no-parsefloat-numeric', originalReport);
+
+    // List of identifiers that strongly suggest monetary/numeric origin from the DB
+    const MONEY_VARS = ['amount', 'balance', 'total', 'xlm', 'usd', 'quantity'];
+
+    return {
+      CallExpression(node) {
+        let isFlagged = false;
+        
+        if (node.callee.type === 'Identifier' && (node.callee.name === 'parseFloat' || node.callee.name === 'Number')) {
+          if (node.arguments.length > 0 && node.arguments[0].type === 'Identifier') {
+            const argName = node.arguments[0].name.toLowerCase();
+            if (MONEY_VARS.some(v => argName.includes(v))) {
+              isFlagged = true;
+            }
+          }
+          // Also check member expressions (e.g. parseFloat(row.amount))
+          if (node.arguments.length > 0 && node.arguments[0].type === 'MemberExpression') {
+            const prop = node.arguments[0].property;
+            if (prop.type === 'Identifier' && MONEY_VARS.some(v => prop.name.toLowerCase().includes(v))) {
+              isFlagged = true;
+            }
+          }
+        }
+
+        if (isFlagged) {
+          context.report({
+            node,
+            message: "Do not use {{callee}} on monetary values. This causes precision loss. Use a BigNumber library or string-based decimal math.",
+            data: {
+              callee: node.callee.name
+            }
+          });
+        }
+      }
+    };
+  }
+};
diff --git a/scripts/eslint-plugin-greenpay/lib/rules/no-undeclared-reachable.js b/scripts/eslint-plugin-greenpay/lib/rules/no-undeclared-reachable.js
new file mode 100644
index 00000000..885dafe1
--- /dev/null
+++ b/scripts/eslint-plugin-greenpay/lib/rules/no-undeclared-reachable.js
@@ -0,0 +1,72 @@
+const { wrapReport } = require('../utils/baseline');
+
+module.exports = {
+  meta: {
+    type: "problem",
+    docs: {
+      description: "Flag identifiers used in reachable code but never imported or defined",
+      category: "Possible Errors",
+      recommended: true
+    },
+    schema: [] // no options
+  },
+  create: function(context) {
+    const originalReport = context.report;
+    context.report = wrapReport(context, 'greenpay/no-undeclared-reachable', originalReport);
+
+    // Globals allowed in the environments
+    const ALLOWED_GLOBALS = new Set([
+      'console', 'process', 'require', 'module', 'exports', 'window', 'document', 'setTimeout', 'clearTimeout',
+      'Promise', 'Error', 'Buffer', 'Array', 'Object', 'String', 'Number', 'Boolean', 'JSON', 'Math', 'Date',
+      'fetch', 'describe', 'it', 'beforeEach', 'afterEach', 'expect', 'jest', '__dirname', 'global', 'localStorage'
+    ]);
+
+    return {
+      Identifier(node) {
+        // We only care about variables being read
+        // Check if it's part of a declaration, assignment, property of an object, etc.
+        const parent = node.parent;
+        
+        // Ignore properties like obj.foo
+        if (parent.type === 'MemberExpression' && parent.property === node && !parent.computed) {
+          return;
+        }
+
+        // Ignore object keys like { foo: 1 }
+        if (parent.type === 'Property' && parent.key === node) {
+          return;
+        }
+        
+        // Ignore variable declarations, function parameters
+        if (parent.type === 'VariableDeclarator' && parent.id === node) return;
+        if (parent.type === 'FunctionDeclaration' && (parent.id === node || parent.params.includes(node))) return;
+        if (parent.type === 'ArrowFunctionExpression' && parent.params.includes(node)) return;
+
+        // Try to resolve in the ESLint scope
+        const scope = context.getScope();
+        
+        // check if it's declared in current or any upper scope
+        let currentScope = scope;
+        let isDefined = false;
+        
+        while (currentScope) {
+          if (currentScope.set.has(node.name)) {
+            isDefined = true;
+            break;
+          }
+          currentScope = currentScope.upper;
+        }
+        
+        if (!isDefined && !ALLOWED_GLOBALS.has(node.name)) {
+          context.report({
+            node,
+            message: "'{{name}}' is used but never imported or defined.",
+            data: {
+              name: node.name
+            }
+          });
+        }
+      }
+    };
+  }
+};
diff --git a/scripts/eslint-plugin-greenpay/lib/utils/baseline.js b/scripts/eslint-plugin-greenpay/lib/utils/baseline.js
new file mode 100644
index 00000000..569c5d69
--- /dev/null
+++ b/scripts/eslint-plugin-greenpay/lib/utils/baseline.js
@@ -0,0 +1,88 @@
+const fs = require('fs');
+const path = require('path');
+
+let baselineSuppression = null;
+
+/**
+ * Loads the baseline suppression file once
+ */
+function loadBaseline() {
+  if (baselineSuppression !== null) {
+    return baselineSuppression;
+  }
+
+  // Look for .greenpay-eslint-baseline.json in the repository root
+  // We assume the plugin is executed from the repository root (e.g. frontend/ or backend/ directory)
+  // But wait! frontend/ and backend/ are subdirectories.
+  // We should resolve the repo root.
+  const repoRoot = path.resolve(__dirname, '../../../../');
+  const baselinePath = path.join(repoRoot, '.greenpay-eslint-baseline.json');
+
+  try {
+    if (fs.existsSync(baselinePath)) {
+      const content = fs.readFileSync(baselinePath, 'utf8');
+      baselineSuppression = JSON.parse(content);
+    } else {
+      baselineSuppression = {};
+    }
+  } catch (error) {
+    console.error('[eslint-plugin-greenpay] Failed to load baseline JSON', error);
+    baselineSuppression = {};
+  }
+
+  return baselineSuppression;
+}
+
+/**
+ * Normalizes file path to be relative to the repo root
+ */
+function getRelativePath(absolutePath) {
+  const repoRoot = path.resolve(__dirname, '../../../../');
+  if (absolutePath.startsWith(repoRoot)) {
+    return absolutePath.substring(repoRoot.length + 1); // remove leading slash
+  }
+  return absolutePath;
+}
+
+/**
+ * Checks if a specific violation is suppressed in the baseline
+ */
+function isSuppressed(context, ruleId) {
+  const baseline = loadBaseline();
+  if (!baseline || Object.keys(baseline).length === 0) {
+    return false;
+  }
+
+  const filename = context.getFilename();
+  if (!filename) return false;
+
+  const relPath = getRelativePath(filename);
+  
+  if (baseline[relPath] && baseline[relPath][ruleId]) {
+    // If the file + rule is in the baseline, we suppress it completely for now
+    // A more advanced baseline would check line numbers or hashes
+    // Given the prompt requirement to allow adoption without fixing all 98 sites at once,
+    // a file-level + rule-level suppression is generally sufficient for a baseline rollout.
+    return true;
+  }
+
+  return false;
+}
+
+/**
+ * Wrap context.report to intercept violations
+ */
+function wrapReport(context, ruleId, reportFn) {
+  return function(descriptor) {
+    if (isSuppressed(context, ruleId)) {
+      return; // Squelched by baseline
+    }
+    return reportFn.call(context, descriptor);
+  };
+}
+
+module.exports = {
+  loadBaseline,
+  isSuppressed,
+  wrapReport,
+};
diff --git a/scripts/eslint-plugin-greenpay/tests/index.test.js b/scripts/eslint-plugin-greenpay/tests/index.test.js
new file mode 100644
index 00000000..ac7bdc6d
--- /dev/null
+++ b/scripts/eslint-plugin-greenpay/tests/index.test.js
@@ -0,0 +1,58 @@
+const { RuleTester } = require('eslint');
+const noParsefloatNumeric = require('../lib/rules/no-parsefloat-numeric');
+const noNestedEnvelope = require('../lib/rules/no-nested-envelope');
+const noCrossPackageImports = require('../lib/rules/no-cross-package-imports');
+const noUndeclaredReachable = require('../lib/rules/no-undeclared-reachable');
+
+const tester = new RuleTester({ parserOptions: { ecmaVersion: 2021, sourceType: 'module' } });
+
+// Tests for no-parsefloat-numeric
+tester.run('no-parsefloat-numeric', noParsefloatNumeric, {
+  valid: [
+    { code: "const val = new BigNumber(amount);" },
+    { code: "parseInt('123', 10);" },
+    { code: "parseFloat(someRandomString);" }
+  ],
+  invalid: [
+    {
+      code: "const x = parseFloat(amount);",
+      errors: [{ message: "Do not use parseFloat on monetary values. This causes precision loss. Use a BigNumber library or string-based decimal math." }]
+    },
+    {
+      code: "const y = Number(row.total);",
+      errors: [{ message: "Do not use Number on monetary values. This causes precision loss. Use a BigNumber library or string-based decimal math." }]
+    }
+  ]
+});
+
+// Tests for no-nested-envelope
+tester.run('no-nested-envelope', noNestedEnvelope, {
+  valid: [
+    { code: "const data = res.data;" },
+    { code: "const info = response.data;" }
+  ],
+  invalid: [
+    {
+      code: "const info = res.data.data;",
+      errors: [{ message: "Unnecessary nested '.data.data' envelope read. The Axios interceptor already unwraps responses." }],
+      output: "const info = res.data;"
+    }
+  ]
+});
+
+// Tests for no-cross-package-imports
+tester.run('no-cross-package-imports', noCrossPackageImports, {
+  valid: [
+    { code: "import { foo } from '@shared/utils';", filename: "/home/user/repo/frontend/src/index.js" },
+    { code: "import { bar } from './local';", filename: "/home/user/repo/frontend/src/index.js" }
+  ],
+  invalid: [
+    {
+      code: "import { db } from '../../backend/src/db';",
+      filename: "/home/user/repo/frontend/src/index.js",
+      errors: [{ message: "Cross-package boundary violation: Cannot import backend module from outside backend." }]
+    }
+  ]
+});
+
+console.log("All rule tests passed.");