{"slug": "audit-your-codebase-before-migrating-to-stateless-mcp", "title": "Audit Your Codebase Before Migrating to Stateless MCP", "summary": "A developer built a dependency scanner to audit codebases before migrating to the stateless MCP 2026-07-28 protocol, which removes session IDs and initialization handshakes. The tool classifies matches by migration risk and produces a staged rollout checklist, emphasizing that stateless protocol does not mean the application has no state.", "body_md": "MCP 2026-07-28 removes protocol-level sessions, the required initialization handshake, and `Mcp-Session-Id`\n\n. Before deleting those code paths, find the application state they were hiding. This tutorial builds a dependency scanner, classifies each match by migration risk, and turns the results into a staged rollout checklist.\n\nThis is a static audit, not proof that a deployment is compatible. It finds likely legacy assumptions; you still need runtime tests across clients, servers, gateways, and replicas.\n\nWhat changed?\n\nThe [official MCP 2026-07-28 changelog](https://modelcontextprotocol.io/specification/2026-07-28/changelog) makes several changes that affect production architecture:\n\n`Mcp-Session-Id`\n\nis removed from Streamable HTTP.`initialize`\n\nand `notifications/initialized`\n\nare no longer required.`_meta`\n\n.`server/discover`\n\nfor version and capability discovery.`Mcp-Method`\n\nand `Mcp-Name`\n\nsupport HTTP routing and policy.`ttlMs`\n\nand `cacheScope`\n\n.`includeContext`\n\nvalues, and Dynamic Client Registration are deprecated rather than immediately removed.The risky misunderstanding is that “stateless protocol” means “the application has no state.” A workspace, durable task, OAuth credential, or pending approval can still span calls. The dependency must simply be explicit and available to any compatible worker that receives the next request.\n\nThe following Node.js script searches a repository for older MCP assumptions. It uses only Node’s standard library and produces both a readable report and an optional JSON report for CI.\n\nCreate `audit-mcp-2026.mjs`\n\n:\n\n``` python\n#!/usr/bin/env node\n\nimport { promises as fs } from \"node:fs\";\nimport path from \"node:path\";\nimport process from \"node:process\";\n\nconst rules = [\n  {\n    id: \"protocol-session\",\n    risk: \"high\",\n    pattern: /Mcp-Session-Id|ctx\\.sessionId|extra\\.sessionId|sessionId/g,\n    action: \"Map the state behind the session, then use an explicit handle or shared storage.\",\n  },\n  {\n    id: \"initialization-gate\",\n    risk: \"medium\",\n    pattern: /notifications\\/initialized|\\binitialize\\b/g,\n    action: \"Remove gates for modern requests and add server/discover plus version negotiation.\",\n  },\n  {\n    id: \"sticky-routing\",\n    risk: \"high\",\n    pattern: /sticky[_-]?session|sessionAffinity|affinity:\\s*(?:ClientIP|cookie)/gi,\n    action: \"Test consecutive calls on different replicas before removing affinity.\",\n  },\n  {\n    id: \"server-initiated-request\",\n    risk: \"high\",\n    pattern: /elicitation\\/create|sampling\\/createMessage|roots\\/list/g,\n    action: \"Move interaction to MRTR and make retried side effects idempotent.\",\n  },\n  {\n    id: \"legacy-resource-subscription\",\n    risk: \"medium\",\n    pattern: /resources\\/(?:subscribe|unsubscribe)|Last-Event-ID/g,\n    action: \"Plan subscriptions/listen and test broken-stream behavior.\",\n  },\n  {\n    id: \"legacy-task\",\n    risk: \"medium\",\n    pattern: /tasks\\/(?:result|list)/g,\n    action: \"Adopt the io.modelcontextprotocol/tasks extension contract.\",\n  },\n  {\n    id: \"legacy-logging\",\n    risk: \"low\",\n    pattern: /logging\\/setLevel|notifications\\/message/g,\n    action: \"Review per-request log metadata and production observability.\",\n  },\n];\n\nconst ignoredDirectories = new Set([\n  \".git\",\n  \"node_modules\",\n  \"dist\",\n  \"build\",\n  \"coverage\",\n  \"vendor\",\n]);\n\nconst textExtensions = new Set([\n  \".cjs\", \".conf\", \".go\", \".java\", \".js\", \".json\", \".jsx\",\n  \".md\", \".mjs\", \".py\", \".rb\", \".rs\", \".sh\", \".toml\",\n  \".ts\", \".tsx\", \".yaml\", \".yml\",\n]);\n\nfunction parseArguments(argv) {\n  const result = { root: \".\", json: false };\n\n  for (const argument of argv) {\n    if (argument === \"--json\") result.json = true;\n    else if (argument.startsWith(\"-\")) {\n      throw new Error(`Unknown option: ${argument}`);\n    } else result.root = argument;\n  }\n\n  return result;\n}\n\nasync function* walk(directory) {\n  const entries = await fs.readdir(directory, { withFileTypes: true });\n\n  for (const entry of entries) {\n    if (ignoredDirectories.has(entry.name)) continue;\n\n    const fullPath = path.join(directory, entry.name);\n    if (entry.isDirectory()) yield* walk(fullPath);\n    else if (entry.isFile() && textExtensions.has(path.extname(entry.name))) {\n      yield fullPath;\n    }\n  }\n}\n\nfunction scanLine(line, file, lineNumber) {\n  const findings = [];\n\n  for (const rule of rules) {\n    rule.pattern.lastIndex = 0;\n    const matches = [...line.matchAll(rule.pattern)];\n    for (const match of matches) {\n      findings.push({\n        file,\n        line: lineNumber,\n        column: (match.index ?? 0) + 1,\n        match: match[0],\n        rule: rule.id,\n        risk: rule.risk,\n        action: rule.action,\n      });\n    }\n  }\n\n  return findings;\n}\n\nasync function audit(root) {\n  const absoluteRoot = path.resolve(root);\n  const findings = [];\n\n  for await (const file of walk(absoluteRoot)) {\n    const content = await fs.readFile(file, \"utf8\");\n    const lines = content.split(/\\r?\\n/);\n\n    lines.forEach((line, index) => {\n      findings.push(\n        ...scanLine(line, path.relative(absoluteRoot, file), index + 1),\n      );\n    });\n  }\n\n  return findings;\n}\n\nfunction printText(findings) {\n  if (findings.length === 0) {\n    console.log(\"No known legacy MCP patterns found. Runtime testing is still required.\");\n    return;\n  }\n\n  const weight = { high: 0, medium: 1, low: 2 };\n  findings.sort((a, b) => weight[a.risk] - weight[b.risk]);\n\n  for (const finding of findings) {\n    console.log(\n      `[${finding.risk.toUpperCase()}] ${finding.file}:${finding.line}:${finding.column} ` +\n      `${finding.rule} (${finding.match})`,\n    );\n    console.log(`  ${finding.action}`);\n  }\n\n  const counts = findings.reduce(\n    (summary, item) => ({ ...summary, [item.risk]: summary[item.risk] + 1 }),\n    { high: 0, medium: 0, low: 0 },\n  );\n  console.log(`\\nSummary: ${counts.high} high, ${counts.medium} medium, ${counts.low} low`);\n}\n\nasync function main() {\n  const options = parseArguments(process.argv.slice(2));\n  const findings = await audit(options.root);\n\n  if (options.json) console.log(JSON.stringify({ findings }, null, 2));\n  else printText(findings);\n\n  process.exitCode = findings.some((item) => item.risk === \"high\") ? 2 : 0;\n}\n\nmain().catch((error) => {\n  console.error(error instanceof Error ? error.message : error);\n  process.exitCode = 1;\n});\n```\n\nThe script requires Node.js 20 or later. Run it from any directory and pass the repository path:\n\n```\nnode audit-mcp-2026.mjs /path/to/your/repository\n```\n\nUse JSON output in CI or to create migration tickets:\n\n```\nnode audit-mcp-2026.mjs /path/to/your/repository --json > mcp-audit.json\n```\n\nThe exit codes are:\n\n| Code | Meaning |\n|---|---|\n`0` |\nNo high-risk static match was found |\n`1` |\nThe scanner itself failed |\n`2` |\nAt least one high-risk pattern was found |\n\nDo not fail a production release merely because a string appears in documentation or a compatibility test. Treat each finding as a review item. The script intentionally favors visibility over certainty.\n\nA grep result is not a migration plan. For each high-risk match, record:\n\nThe common replacement patterns are explicit handles and shared storage. An explicit handle makes the dependency visible in the tool schema. Shared storage makes the state accessible across replicas and restarts. Long-running work belongs in a durable task system rather than the memory of a request worker.\n\nStatic scanning cannot detect whether a retry is safe or whether an authorization boundary is correct. Add integration tests that deliberately exercise the new architecture.\n\n`input_required`\n\nbefore the side effect.`requestState`\n\n; both cases must fail closed.Send a request whose `Mcp-Name`\n\nidentifies a low-risk tool while the JSON-RPC body calls a restricted tool. The request should be rejected and the mismatch should appear in security telemetry.\n\nFetch a private tool or resource list as tenant A, then request the same method as tenant B. The second tenant must never receive A’s entry, regardless of the remaining TTL.\n\nA safe rollout keeps modern and legacy behavior observable at the same time. Test these combinations explicitly:\n\n``` php\nmodern client + modern server    -> MCP 2026-07-28\nmodern client + legacy server    -> tested fallback, if supported\nlegacy client + dual server      -> legacy path\nunsupported combination         -> clear protocol-version error\n```\n\nTrack protocol version, discovery success, fallback rate, missing or invalid headers, header/body mismatches, MRTR completion and timeout, request-state verification, duplicate-operation prevention, cache hits by scope, OAuth issuer failures, legacy HTTP+SSE traffic, and deprecated-method traffic.\n\nRetire a compatibility path because the telemetry says it is unused—not because a calendar says the upgrade should be complete.\n\nMCP and a model API solve different problems. MCP connects an agent to tools, resources, approvals, and tasks. A model API connects an application to inference providers, credentials, usage, and billing.\n\nWhen migrating away from the deprecated Sampling capability, an application can call a model provider directly or use a unified model layer such as CometAPI. That model layer does not replace MCP authorization, tool contracts, application state, or MRTR handling. Keeping the interfaces separate simply allows the protocol and inference providers to evolve independently.\n\n`server/discover`\n\nand version negotiation.`requestState`\n\n.MCP 2026-07-28 removes sessions from the protocol contract, not from every application requirement. The migration succeeds when any compatible worker can process the next request from explicit inputs, every retry is authorized and idempotent, and the legacy path can be retired from evidence.", "url": "https://wpnews.pro/news/audit-your-codebase-before-migrating-to-stateless-mcp", "canonical_source": "https://dev.to/develmilk/audit-your-codebase-before-migrating-to-stateless-mcp-317f", "published_at": "2026-07-30 07:32:23+00:00", "updated_at": "2026-07-30 08:01:38.936814+00:00", "lang": "en", "topics": ["developer-tools", "ai-infrastructure"], "entities": ["MCP"], "alternates": {"html": "https://wpnews.pro/news/audit-your-codebase-before-migrating-to-stateless-mcp", "markdown": "https://wpnews.pro/news/audit-your-codebase-before-migrating-to-stateless-mcp.md", "text": "https://wpnews.pro/news/audit-your-codebase-before-migrating-to-stateless-mcp.txt", "jsonld": "https://wpnews.pro/news/audit-your-codebase-before-migrating-to-stateless-mcp.jsonld"}}