# Developer Protocol **Server:** coingecko-mcp-server **Version:** 0.2.0 **Framework:** [@cyanheads/mcp-ts-core](https://www.npmjs.com/package/@cyanheads/mcp-ts-core) `^0.13.15` **Engines:** Bun ≥1.4.0, Node ≥24.0.0 **MCP SDK:** `@modelcontextprotocol/server` ^2.3.1 **Zod:** ^4.6.6 > **Read the framework docs first:** `node_modules/@cyanheads/mcp-ts-core/CLAUDE.md` contains the full API reference — builders, Context, error codes, exports, patterns. This file covers server-specific conventions only. --- ## What's Next? When the user asks what's next or needs direction, suggest options based on the current project state. Common next steps: 1. **Re-run the `setup` skill** — ensures CLAUDE.md, skills, structure, and metadata are populated and up to date with the current codebase 2. **Run the `design-mcp-server` skill** — if the tool/resource surface hasn't been mapped yet, work through domain design 3. **Add tools/resources/prompts** — scaffold new definitions using the `add-tool`, `add-app-tool`, `add-resource`, `add-prompt` skills 4. **Add services** — scaffold domain service integrations using the `add-service` skill 5. **Add tests** — scaffold tests for existing definitions using the `add-test` skill 6. **Field-test definitions** — exercise tools/resources/prompts with real inputs using the `field-test` skill, get a report of issues and pain points 7. **Run `devcheck`** — lint, format, typecheck, and security audit 8. **Run the `security-pass` skill** — audit handlers for MCP-specific security gaps: output injection, scope blast radius, input sinks, tenant isolation 9. **Run the `polish-docs-meta` skill** — finalize README, CHANGELOG, metadata, and agent protocol for shipping 10. **Run the `maintenance` skill** — investigate changelogs, adopt upstream changes, and sync skills after `bun update --latest` Tailor suggestions to what's actually missing or stale — don't recite the full list every time. --- ## Core Rules - **Logic throws, framework catches.** Tool/resource handlers are pure — throw on failure, no `try/catch`. Plain `Error` is fine; the framework catches, classifies, and formats. Use error factories (`notFound()`, `validationError()`, etc.) when the error code matters. - **Use `ctx.log`** for request-scoped logging. No `console` calls. - **Use `ctx.state`** for tenant-scoped storage. Never access persistence directly. - **Need input the caller didn't supply?** `return ctx.requestInput(...)` and read `ctx.inputs` when the handler is re-entered. Never `await` for user input mid-handler. - **Secrets in env vars only** — never hardcoded. - **Cut noise.** Add only what earns its place: no speculative generality, no guards for states the framework already prevents (Zod-validated params, classified errors), no abstraction until a third caller proves it, no option nothing sets. - **Close the loop on issues.** When implementing work tracked by a GitHub issue, comment on the issue with what landed and close it. Do both — a comment without a close leaves stale issues open; a close without a comment leaves no record of what shipped. The comment is for future readers — state the concrete changes, not the conversation that produced them. --- ## Patterns ### Tool ```ts import { tool, z } from '@cyanheads/mcp-ts-core'; import { getCoinGeckoService } from '@/services/coingecko/coingecko-service.js'; import { COINGECKO_ATTRIBUTION } from '@/services/coingecko/types.js'; export const searchCoinsTool = tool('coingecko_search_coins', { title: 'coingecko-mcp-server: search coins', description: 'Resolve a coin name or ticker symbol to a CoinGecko ID (slug). The required first step before any ID-keyed tool — CoinGecko keys data by slug (bitcoin, ethereum), not ticker (BTC, ETH).', annotations: { readOnlyHint: true, idempotentHint: true, openWorldHint: true }, input: z.object({ query: z.string().min(1).describe('Coin name or ticker symbol to resolve (e.g. "bitcoin", "ETH").'), }), output: z.object({ coins: z.array(z.object({ id: z.string().describe('CoinGecko slug — the id to chain into every other tool.'), symbol: z.string().describe('Ticker symbol (not unique across coins).'), name: z.string().describe('Display name.'), })).describe(`Ranked slug candidates. ${COINGECKO_ATTRIBUTION}.`), attribution: z.string().describe('Required data-source attribution.'), }), async handler(input, ctx) { ctx.log.info('coingecko_search_coins', { query: input.query }); const coins = await getCoinGeckoService().search(input.query, ctx); return { coins, attribution: COINGECKO_ATTRIBUTION }; }, // format() populates content[] — the markdown twin of structuredContent. // Different clients read different surfaces (Claude Code → structuredContent, // Claude Desktop → content[]); both must carry the same data. // Enforced at lint time: every field in `output` must appear in the rendered text. format: (result) => [{ type: 'text', text: result.coins.map((c) => `**${c.name}** (${c.symbol}) — id: \`${c.id}\``).join('\n'), }], }); ``` ### Resource ```ts import { resource, z } from '@cyanheads/mcp-ts-core'; import { JsonRpcErrorCode } from '@cyanheads/mcp-ts-core/errors'; import { getCoinGeckoService } from '@/services/coingecko/coingecko-service.js'; import { COINGECKO_ATTRIBUTION } from '@/services/coingecko/types.js'; export const coinResource = resource('coingecko://coin/{id}', { name: 'coingecko-mcp-server: coin record', description: 'Deep coin record by CoinGecko slug — same data as coingecko_get_coin.', mimeType: 'application/json', errors: [ { reason: 'coin_not_found', code: JsonRpcErrorCode.NotFound, when: 'Upstream returned 404 for the slug — it is not a recognized CoinGecko id.', recovery: 'Verify the slug with coingecko_search_coins — IDs are slugs (bitcoin), not tickers (BTC).' }, ], params: z.object({ id: z.string().min(1).describe('CoinGecko slug (e.g. "bitcoin").') }), async handler(params, ctx) { const detail = await getCoinGeckoService().coinDetail(params.id, 'usd', ctx); if (!detail) throw ctx.fail('coin_not_found', `Coin "${params.id}" not found.`, { id: params.id, ...ctx.recoveryFor('coin_not_found'), }); return { ...detail, attribution: COINGECKO_ATTRIBUTION }; }, }); ``` ### Prompt ```ts import { prompt, z } from '@cyanheads/mcp-ts-core'; export const coinResearchPrompt = prompt('coingecko_coin_research', { title: 'coingecko-mcp-server: coin research', description: 'Structures a full single-coin research pass — guides the agent through the search → get_coin → get_market_chart → get_global chain.', args: z.object({ coin: z.string().min(1).describe('The coin to research — a name, ticker, or CoinGecko slug.'), }), generate: (args) => [ { role: 'user' as const, content: { type: 'text' as const, text: `Research the cryptocurrency: **${args.coin}**. Resolve its slug with coingecko_search_coins first, then pull its profile, sample recent price history, and frame it against the global market.`, }, }, ], }); ``` ### Server config This server runs keyless by default — the one optional var attaches the Demo-tier header. `parseEnvConfig` reads an empty string and an unsubstituted MCPB `${user_config.X}` placeholder as unset, so a blank Claude Desktop field never sends a garbage header — no per-field `z.preprocess` guard. ```ts // src/config/server-config.ts — lazy-parsed, separate from framework config import { z } from '@cyanheads/mcp-ts-core'; import { parseEnvConfig } from '@cyanheads/mcp-ts-core/config'; const ServerConfigSchema = z.object({ apiKey: z .string() .optional() .describe('Optional CoinGecko Demo API key (x-cg-demo-api-key header). Absent → keyless tier.'), }); let _config: z.infer | undefined; export function getServerConfig() { _config ??= parseEnvConfig(ServerConfigSchema, { apiKey: 'COINGECKO_API_KEY' }); return _config; } ``` `parseEnvConfig` maps Zod schema paths → env var names so errors name the variable (`COINGECKO_API_KEY`) not the path (`apiKey`). Throws `ConfigurationError`, which the framework prints as a clean startup banner. For env booleans use `z.stringbool()`, never `z.coerce.boolean()` — `Boolean("false")` is `true`, so a coerced flag can't be disabled through the environment. `z.stringbool()` parses `true/false/1/0/yes/no/on/off` and rejects anything else, so `=false` actually disables. ### Server identity and instructions `createApp()` accepts optional identity fields forwarded to the SDK's `initialize` response and the server manifest (`/.well-known/mcp.json`): Display identity is the machine name on every surface — `name` and `title` are both `coingecko-mcp-server`, never a Title Case form. `description` is not set here; it derives from `package.json` (the canonical source). ```ts await createApp({ name: 'coingecko-mcp-server', title: 'coingecko-mcp-server', // display name = the machine name, always instructions: // session-level context, sent on every initialize 'Cryptocurrency market data from CoinGecko. Data is keyed by slug (bitcoin), NOT ticker (BTC) — resolve names/tickers with coingecko_search_coins FIRST, then chain the id. Data refreshes ~every 60s. Runs keyless by default. Data provided by CoinGecko.', // ...tools, resources, prompts, setup() }); ``` `instructions` is optional server-level orientation, sent on every `initialize` as session-level context. Use it for cross-tool guidance (here: the slug-not-ticker rule and search-first workflow) instead of repeating the same context across every tool description. Client adoption is uneven, but there's no downside when set. ### Session posture and shutdown Two more `createApp()` options shape how the server runs rather than how it presents itself: ```ts await createApp({ sessionMode: 'stateless', // or { default: 'stateful', require: 'stateful' } setup() { initCoinGeckoService(); }, // teardown(core) { … } // the setup() counterpart — unset here, nothing to release }); ``` This server declares `sessionMode: 'stateless'`: no tool calls `ctx.requestInput` and nothing is held per session. `MCP_SESSION_MODE` still wins whenever it carries a meaningful value (an explicit `auto` resolves to `stateful`); an empty string and an unsubstituted `${…}` placeholder read as unset and fall through to the declared `stateless`. A tool that asks the caller for input mid-handler needs `{ default: 'stateful', require: 'stateful' }` instead — startup then fails with a `ConfigurationError` rather than serving a mode in which a 2025-era client can never answer the prompt. Stdio is never refused. `teardown(core)` is the `setup()` counterpart — release a watcher, socket, or non-`unref()`'d timer there. It runs after the transport stops and before the logger closes, on every shutdown path, and a signal-triggered shutdown then exits the process explicitly (0, or 1 if a step never settles within the framework's 10 s ceiling). The CoinGecko service allocates none of these, so this server sets no `teardown`. --- ## Context Handlers receive a unified `ctx` object. Key properties: This is a stateless, read-only server — it uses `ctx.log`, `ctx.enrich`, `ctx.fail`/`ctx.recoveryFor`, and `ctx.signal`. It does not use `ctx.state`, `ctx.elicit`, or `ctx.progress`. | Property | Description | |:---------|:------------| | `ctx.log` | Request-scoped logger — `.debug()`, `.info()`, `.notice()`, `.warning()`, `.error()`. Auto-correlates requestId, traceId, tenantId. Dual-sink: Pino and `notifications/message` to the client, so treat it as client-visible. | | `ctx.enrich` | Attach non-payload metadata to the response — `ctx.enrich.notice(msg)`, `ctx.enrich.truncated({ shown, cap })`, `ctx.enrich.total(n)`, or `ctx.enrich({ ...fields })`. Reaches both `structuredContent` and `content[]` only when the definition declares an `enrichment` block; otherwise it is a no-op. Shapes match the tool's `enrichment` schema. Used here to disclose truncation, dropped ids/currencies, and applied filters. | | `ctx.fail` / `ctx.recoveryFor` | Throw a typed contract error against the tool's `errors[]` reason union — `throw ctx.fail('coin_not_found', msg)`. Declared recovery hints are filled at the response boundary; explicit hints override them. | | `ctx.signal` | `AbortSignal` for cancellation, forwarded to `fetchWithTimeout`. | | `ctx.requestId` | Unique request ID. | | `ctx.tenantId` | Tenant ID from JWT or `'default'` for stdio. | --- ## Errors Handlers throw — the framework catches, classifies, and formats. **Recommended: typed error contract.** Declare `errors: [{ reason, code, when, recovery, retryable?, severity?, thrownBy? }]` on `tool()` / `resource()` to receive `ctx.fail(reason, …)` typed against the reason union. TypeScript catches typos at compile time, `data.reason` is auto-populated for observability, linter enforces conformance against the handler body. `recovery` is required (≥ 5 words, lint-validated) — the single source of truth for the agent's next move. The framework puts it on the wire whenever a failure carrying that `reason` arrives without a hint — a bare `ctx.fail('reason')` or a service throw with `data: { reason }` — as `data.recovery.hint`, mirrored into `content[]` text unless the message already contains it verbatim; override with an explicit `{ recovery: { hint: '...' } }` when dynamic runtime context matters. Every error envelope also carries `data.requestId`, the id the server's log records for that call carry, and `content[]` closes with `(reason … · request )`. Mark an entry the service layer throws with `thrownBy: 'service'` so `error-contract-unthrown` skips it — lint-only metadata, nothing at runtime reads it. Baseline codes (`InternalError`, `ServiceUnavailable`, `Timeout`, `ValidationError`, `SerializationError`, `RequestCancelled`) bubble freely and don't need declaring. ```ts import { JsonRpcErrorCode } from '@cyanheads/mcp-ts-core/errors'; errors: [ { reason: 'coin_not_found', code: JsonRpcErrorCode.NotFound, when: 'Upstream returned 404 for the slug — it is not a recognized CoinGecko id.', recovery: 'Verify the slug with coingecko_search_coins — IDs are slugs (bitcoin), not tickers (BTC).' }, ], async handler(input, ctx) { const detail = await getCoinGeckoService().coinDetail(input.id, input.vs_currency, ctx); if (!detail) throw ctx.fail('coin_not_found', `Coin "${input.id}" not found.`, { id: input.id, ...ctx.recoveryFor('coin_not_found'), }); return detail; } ``` This server centralizes transport reasons in `src/services/coingecko/error-contracts.ts` and spreads `...COINGECKO_SERVICE_ERRORS` into each tool's `errors[]`. Reasons retain the installed framework's status/code/retry mapping, distinguish permanent refusals, timeouts, rate limits, and transient failures, and carry bounded explanations from confirmed JSON envelopes. History error 10012 recommends a narrower window. Every shared entry carries `thrownBy: 'service'`, as do inline `unsupported_currency` contracts raised by `global()` or `coinDetail()`. Coin detail validates only market-selected missing quote keys against the supported-currency catalog; primary/supplemental calls and retries share a 50-second deadline. Tool handlers rely on declared recovery fill; service throws keep hints for resources too. This shared transport contract is the exception to inline-only `errors[]` because every tool calls the same HTTP client. **Declare contracts inline on each tool.** The contract is part of the tool's public surface — one file should give the full picture. Don't extract a shared `errors[]` constant; per-tool repetition is the intended cost of locality. **Fallback (no contract entry fits):** throw via factories or plain `Error`. ```ts // Error factories — explicit code import { notFound, serviceUnavailable } from '@cyanheads/mcp-ts-core/errors'; throw notFound('Item not found', { itemId }); throw serviceUnavailable('API unavailable', { url }, { cause: err }); // Plain Error — framework auto-classifies from message patterns throw new Error('Item not found'); // → NotFound throw new Error('Invalid query format'); // → ValidationError // McpError — when no factory exists for the code import { McpError, JsonRpcErrorCode } from '@cyanheads/mcp-ts-core/errors'; throw new McpError(JsonRpcErrorCode.InitializationFailed, 'Connection failed', { pool: 'primary' }); ``` See framework CLAUDE.md and the `api-errors` skill for the full auto-classification table, all available factories, and the contract reference. --- ## Structure ```text src/ index.ts # createApp() entry point — registers the surface, inits the service config/ server-config.ts # Optional COINGECKO_API_KEY (Zod schema) services/ coingecko/ api-client.ts # Low-level HTTP client — URL build, Demo-key header, error-envelope mapping coingecko-service.ts # init/accessor service — one method per endpoint, withRetry + normalization error-contracts.ts # Shared service reasons (rate_limited, upstream_unreachable, …) + recoveryFor types.ts # Raw upstream shapes + normalized domain types + COINGECKO_ATTRIBUTION mcp-server/ tools/definitions/ # 8 tools: search-coins, get-prices, list-categories, list-markets, # get-coin, get-market-chart, get-trending, get-global resources/definitions/ # 2 resources: coin (coingecko://coin/{id}), global (coingecko://global) prompts/definitions/ # 1 prompt: coin-research (coingecko_coin_research) ``` --- ## Naming | What | Convention | Example | |:-----|:-----------|:--------| | Files | kebab-case with suffix | `search-docs.tool.ts` | | Tool/resource/prompt names | snake_case | `search_docs` | | Directories | kebab-case | `src/services/doc-search/` | | Descriptions | Single string or template literal, no `+` concatenation | `'Search items by query and filter.'` | --- ## Skills Skills are modular instructions in `framework-skills/` at the project root. Read them directly when a task matches — e.g., `framework-skills/add-tool/SKILL.md` when adding a tool. `bun run list-skills` prints the full registry. The directory is deliberately not `skills/`: Claude Code and Codex auto-load a plugin's root `skills/`, so a server that ships `.claude-plugin/` or `.codex-plugin/` would hand these development skills to every agent that installs it. Keep `skills/` free for skills meant for those agents. **Agent skill directory:** Copy skills into the directory your agent discovers (Claude Code: `.claude/skills/`, others: equivalent). Skills then load as context without referencing `framework-skills/` paths. After framework updates, run the `maintenance` skill — Phase B re-syncs the agent directory. Available skills: | Skill | Purpose | |:------|:--------| | `setup` | Post-init project orientation | | `design-mcp-server` | Design tool surface, resources, and services for a new server | | `add-tool` | Scaffold a new tool definition | | `add-app-tool` | Scaffold an MCP App tool + paired UI resource | | `add-resource` | Scaffold a new resource definition | | `add-prompt` | Scaffold a new prompt definition | | `add-service` | Scaffold a new service integration | | `add-test` | Scaffold test file for a tool, resource, or service | | `field-test` | Exercise tools/resources/prompts with real inputs, verify behavior, report issues | | `tool-defs-analysis` | Read-only audit of MCP definition language across the surface — voice, leaks, defaults, recovery hints, output descriptions | | `security-pass` | Audit server for MCP-flavored security gaps: output injection, scope blast radius, input sinks, tenant isolation | | `code-simplifier` | Post-session cleanup against `git diff` — modernize syntax, consolidate duplication, align with the codebase | | `polish-docs-meta` | Finalize docs, README, metadata, and agent protocol for shipping | | `git-wrapup` | Land working-tree changes as a commit stack — version bump, changelog, verify, commit by concern, release commit on top. No tag, no push to main; opens the release PR when the project declares release PR mode | | `release-pr-review` | Review pass on an open release PR — simplifier + correctness review, fixes as ordinary commits on top of the stack, PR body kept in sync. Release PR mode only | | `release-and-publish` | Fast-forward merge (release PR mode) + tag + push + npm + MCP Registry + GH Release + Docker. Picks up from `git-wrapup` | | `maintenance` | Investigate changelogs, adopt upstream changes, sync skills to agent dirs | | `orchestrations` | Chain task skills into a gated multi-phase pipeline — build-out, QA-fix, update-ship — when you can spawn sub-agents | | `report-issue-framework` | File a bug or feature request against `@cyanheads/mcp-ts-core` via `gh` CLI | | `report-issue-local` | File a bug or feature request against this server's own repo via `gh` CLI | | `techniques` | Catalog of response/data-shaping techniques — overflow handling, payload shaping, retrieval patterns | | `api-auth` | Auth modes, scopes, JWT/OAuth | | `api-canvas` | DataCanvas: register tabular data, run SQL, export, plus the `spillover()` helper for big result sets — Tier 3 opt-in | | `api-config` | AppConfig, parseConfig, env vars | | `api-context` | Context interface, RequestContext, logger, state, multi-round-trip input | | `api-errors` | McpError, JsonRpcErrorCode, error patterns | | `api-linter` | Definition linter rule catalog — invoked by `bun run lint:mcp` and `devcheck` | | `api-mirror` | MirrorService: persistent self-refreshing local mirror (embedded SQLite + FTS5) of a bulk upstream dataset — Tier 3 opt-in | | `api-services` | LLM, Speech, Graph services | | `api-testing` | createMockContext, test patterns | | `api-utils` | Formatting, parsing, security, pagination, scheduling, telemetry helpers | | `api-telemetry` | OTel catalog: spans, metrics, completion logs, env config, cardinality rules | | `api-workers` | Cloudflare Workers runtime | **Chaining skills into pipelines.** When the user wants a multi-phase effort — build this server out, QA-and-fix the surface, update-and-ship — *and you can spawn sub-agents*, `framework-skills/orchestrations/SKILL.md` sequences the task skills above into a gated pipeline with verification at each step. Read it to drive the run. Optional: skip it if you can't orchestrate sub-agents, and ignore it entirely if you were *spawned* as one — you've already been scoped to a single phase. When you complete a skill's checklist, check the boxes and add a completion timestamp at the end (e.g., `Completed: 2026-03-11`). --- ## Commands **Runtime:** Scripts use Bun's native TypeScript execution — `bun run ` is the standard invocation. `npm run ` also works (npm delegates to bun). | Command | Purpose | |:--------|:--------| | `bun run build` | Compile TypeScript | | `bun run rebuild` | Clean + build | | `bun run clean` | Remove build artifacts | | `bun run devcheck` | Lint + format + typecheck + security + changelog sync | | `bun run audit:fix` | `bun audit fix` — upgrade vulnerable packages to the lowest safe version within existing ranges (`--dry-run` previews, `--latest` rewrites ranges). First response when `devcheck` flags a transitive advisory; then `bun update `, then `bun dedupe` | | `bun run audit:refresh` | Delete `bun.lock` and reinstall. Last resort after `audit:fix`, `bun update `, and `bun dedupe` — re-resolves every ranged dep (the framework pin included) and rewrites the lockfile as `lockfileVersion: 2` | | `bun run tree` | Generate directory structure doc | | `bun run list-skills` | List the project's available skills and their paths | | `bun run format` | Auto-fix formatting (safe fixes only) | | `bun run format:unsafe` | Also apply Biome's unsafe autofixes — review the diff; they can change behavior | | `bun run lint:mcp` | Validate MCP tool/resource/prompt definitions against the spec | | `bun run lint:packaging` | Verify `manifest.json` ↔ `server.json` env var consistency (run by devcheck) | | `bun run test` | Run tests (Vitest — use `bun run test`, not `bun test`) | | `bun run start:stdio` | Production mode (stdio) | | `bun run start:http` | Production mode (HTTP) | | `bun run changelog:build` | Regenerate `CHANGELOG.md` from `changelog/*.md` | | `bun run changelog:check` | Verify `CHANGELOG.md` is in sync (used by devcheck) | | `bun run bundle` | Build, pack, and clean a `.mcpb` for one-click Claude Desktop install | | `bun run release:github` | Create the GitHub Release from the annotated tag (used by release-and-publish) | **CI is one file.** `.github/workflows/codeql.yml` is the only GitHub Actions workflow: CodeQL is GitHub-owned end to end, and the file runs only while the repo's CodeQL *default setup* is turned off. Verification — `devcheck`, tests, the release gates — runs locally; don't add a workflow that re-runs it. --- ## Bundling `bun run bundle` produces a `.mcpb` extension bundle for one-click install in Claude Desktop. The pack step is followed by `scripts/clean-mcpb.ts`, which prunes dev dependencies (`mcpb clean`), strips platform-specific native bindings for portable bundles, and strips dependency-shipped agent docs (`node_modules/**` `framework-skills/`, `skills/`, `.claude/`, `.agents/`, `SKILL.md`) that root-anchored `.mcpbignore` patterns cannot reach. MCPB is stdio-only — HTTP and Cloudflare Workers deployments are unaffected. Consumers who don't need it can delete `manifest.json` and `.mcpbignore`; `lint:packaging` skips cleanly. **Adding an env var requires both files:** `server.json` (registry discovery, `environmentVariables[]`) and `manifest.json` (bundle install UX, `mcp_config.env` + `user_config`). `lint:packaging` (run by `devcheck`) verifies the env var names match, that every `user_config` option is wired into `mcp_config.env` as `"X": "${user_config.X}"` (the host substitutes nothing else — `"${X}"` reaches the server as that literal string), and that an optional string option carries `"default": ""`. **README install badges** (Claude Desktop `.mcpb`, Cursor, VS Code) and the `base64` / `encodeURIComponent` config-generation commands are ship-time concerns — run the `polish-docs-meta` skill, which carries the badge format, layout, and generation snippets in `framework-skills/polish-docs-meta/references/readme.md`. --- ## Changelog Directory-based, grouped by minor series via the `.x` semver-wildcard convention. Source of truth: `changelog/.x/.md` (e.g. `changelog/0.1.x/0.1.0.md`) — one file per release, shipped in the npm package. At release, author the per-version file with a concrete version and date, then run `bun run changelog:build` to regenerate the rollup. `changelog/template.md` is a **pristine format reference** — never edited or moved; read it for the frontmatter + section layout when scaffolding. `CHANGELOG.md` is a **navigation index** (header + link + summary per version), regenerated by `bun run changelog:build` — devcheck hard-fails on drift; never hand-edit it. Each per-version file opens with YAML frontmatter: ```markdown --- summary: "One-line headline, ≤350 chars" # required — powers the rollup index breaking: false # optional — true flags breaking changes security: false # optional — true ONLY for a source-code security fix, never a dependency CVE bump --- # 0.1.0 — YYYY-MM-DD ... ``` `breaking: true` renders a `· ⚠️ Breaking` badge — use it when consumers must update code on upgrade (signature changes, removed APIs, config renames). `security: true` renders a `· 🛡️ Security` badge and pairs with a `## Security` body section — set it only for a security fix in this server's own source code, never for a dependency or transitive CVE bump (record those under `## Dependencies`). When both are set, badges render `· ⚠️ Breaking · 🛡️ Security`. `agent-notes` is an optional free-form field for maintenance agents processing the release downstream. Content here won't appear in the rendered CHANGELOG — it's consumed by agents running the `maintenance` skill. Use it for adoption instructions that don't fit the human-facing sections: new files to create, fields to populate, one-time migration steps. Omit entirely when there's nothing to say. **Section order:** the Keep a Changelog sequence — Added, Changed, Deprecated, Removed, Fixed, Security — then `Dependencies` last. Include only sections with entries — don't ship empty headers. **Tag annotations** render as GitHub Release bodies via `--notes-from-tag`. They must be structured markdown — never a flat comma-separated string. Subject omits the version number (GitHub prepends it). See `changelog/template.md` for the full format reference. --- ## Publishing **Every release goes through a release PR, straight-through** — `git-wrapup`'s "Release PR mode", mode `straight-through`. One run: `git-wrapup` lands the commit stack on `release/`, pushes it, and opens the PR (title = the release commit subject, body = the release digest: theme line, `## Changes`, `## Gates`, changelog link last); `release-and-publish` then fast-forwards `main` locally with `git merge --ff-only`, creates the tag on `main`'s tip, pushes `main` and the tag, deletes the branch, and publishes. A caller's brief may run a given release as `gated` instead — a `release-pr-review` pass on the open PR before `release-and-publish`. **Never merge through the GitHub UI or `gh pr merge`**: squash and rebase-merge are disabled in the repo settings because both rewrite the stack (rebase-merge also strips the SSH signatures), and a merge commit breaks the linear history. --- ## Imports ```ts // Framework — z is re-exported, no separate zod import needed import { tool, z } from '@cyanheads/mcp-ts-core'; import { McpError, JsonRpcErrorCode } from '@cyanheads/mcp-ts-core/errors'; // Server's own code — via path alias import { getCoinGeckoService } from '@/services/coingecko/coingecko-service.js'; import { COINGECKO_ATTRIBUTION } from '@/services/coingecko/types.js'; ``` --- ## Checklist - [ ] Zod schemas: all fields have `.describe()`, only JSON-Schema-serializable types (no `z.custom()`, `z.date()`, `z.transform()`, `z.bigint()`, `z.symbol()`, `z.void()`, `z.map()`, `z.set()`, `z.function()`, `z.nan()`) - [ ] Optional nested objects: handler guards for empty inner values from form-based clients (`if (input.obj?.field && ...)`, not just `if (input.obj)`). When regex/length constraints matter, use `z.union([z.literal(''), z.string().regex(...).describe(...)])` — literal variants are exempt from `describe-on-fields`. - [ ] JSDoc `@fileoverview` + `@module` on every file - [ ] `ctx.log` for logging; `ctx.enrich` for non-payload metadata (truncation, dropped ids/currencies, applied filters) - [ ] Handlers throw on failure — `ctx.fail` against the tool's `errors[]` contract, factories, or plain `Error`; no try/catch - [ ] Every tool/resource/prompt output carries `COINGECKO_ATTRIBUTION` ("Data provided by CoinGecko") — required by CoinGecko's ToS - [ ] `format()` renders all data the LLM needs — different clients forward different surfaces (Claude Code → `structuredContent`, Claude Desktop → `content[]`); both must carry the same data - [ ] If wrapping external API: raw/domain/output schemas reviewed against real upstream sparsity/nullability before finalizing required vs optional fields - [ ] If wrapping external API: normalization and `format()` preserve uncertainty; do not fabricate facts from missing upstream data - [ ] If wrapping external API: tests include at least one sparse payload case with omitted upstream fields - [ ] Registered in `createApp()` arrays (directly or via barrel exports) - [ ] Tests use `createMockContext()` from `@cyanheads/mcp-ts-core/testing` - [ ] `.codex-plugin/plugin.json` populated — `name`, `version`, `description`, `repository`, `license` from `package.json`; `interface.displayName` = the unscoped repo name (never the npm scope — `lint:packaging` enforces this); `interface.shortDescription` from `package.json` description - [ ] `.codex-plugin/mcp.json` updated — server name key is the unscoped repo name; every user-supplied variable (API key, contact email, instance URL) is listed in `env_vars` so Codex forwards it from the user's environment. Never write `"KEY": ""` into `env` — an empty value replaces the user's exported key and is read as unset - [ ] `.claude-plugin/plugin.json` populated — `name`, `version`, `description`, `author`, `repository`, `license`, `keywords` from `package.json`; inline `mcpServers` entry keyed by the unscoped repo name. Every user-supplied variable is declared under `userConfig` (`type`, `title`, `description`; `sensitive: true` for keys and tokens; `required: true` or `default: ""`) and referenced from `env` as `"KEY": "${user_config.