Skillscript

Catchup ring. Three queued items per Perry's 934fc9d8 sign-off had
been carrying since v0.15.6 (the original two-stage proposal in
0b35bd70) — HttpMcpConnector + contract-test fixture + sibling kwarg
lints. v0.16.4 shipped one (the unknown-llm-model lint) and silently
punted the other three. Warm-adopter flagged "2 releases late" on the
carry-forwards. This ring closes all four.

1. HttpMcpConnector — bundled generic Streamable HTTP MCP connector

Speaks JSON-RPC over HTTP + Server-Sent Events directly — no subprocess
(unlike RemoteMcpConnector + mcp-remote). Substrate-neutral by
design: works against any MCP server speaking the Streamable HTTP spec
(Anthropic's hosted MCP, GitHub MCP, Linear MCP, AMP, etc.) via the
same connector class with different endpoint + headers config.

Adopters declare instances in connectors.json:

{
  "my_remote": {
    "class": "HttpMcpConnector",
    "config": {
      "endpoint": "https://mcp.example.com/",
      "headers": {
        "Authorization": "Bearer ${API_TOKEN}",
        "X-Agent-ID": "${AGENT_ID}"
      }
    },
    "allowed_tools": ["search", "fetch"]
  }
}

Implementation details (per the lift checklist in warm-adopter
memory 41fedec6):

• initialize handshake captures mcp-session-id response header,
  echoes on every subsequent request
• notifications/initialized sent after initialize, before any
  tools/call (protocol-mandatory)
• SSE response parsing handles multi-frame replies (trailing
  notification frame can masquerade as the reply; we take the terminal
  data frame)
• Configurable static auth/identity headers passed through verbatim
• Result unwrap: when content[0].text is JSON-shaped, parse it;
  fallback to raw text or full result block
• staticTools() returns null (runtime-discovered);
  manifest() populates tools_available via tools/list
• Concurrent first-callers share a single handshake (single-flight
  initialization promise)

Source attribution. Lifted + generalized from a warm-adopter's
direct-HTTP MCP client at commit 844a19e in the adopter's tree, per
Perry's 934fc9d8 sign-off. Substrate-specific bits (adopter's tool-
name normalization convenience) stayed adopter-side; only the wire-
layer code was lifted. Generalized substrate-specifics out at the
lift boundary.

2. RuntimeCapabilitiesConformance — discovery-surface contract test

Per Perry's adf47c0b. Closes the long-running discipline-only-
contracts pattern: every flag in runtime_capabilities must have a
matching execution-path probe test. Forces adopters to wire BOTH the
capability declaration AND the dispatch-path probe in lockstep —
without it, the "lint passes, runtime fails" multi-layer-promise
failure mode keeps recurring (5 instances counted pre-v0.15.4 alone).

Exported from skillscript-runtime/testing alongside the existing
five *Conformance objects. Adopters wire it against their runtime:

import { RuntimeCapabilitiesConformance } from "skillscript-runtime/testing";

const fixture = {
  buildRuntime: async () => ({ mcpServer: myWiredRuntime.mcpServer }),
  flagProbes: {
    "shellExecution.unsafe_enabled": async (runtime) => {
      // Probe that unsafe shell ops respect the unsafe_enabled config.
    },
    "localModels[].features.supports_streaming": async (runtime) => {
      // Probe that streaming dispatch is honored when declared.
    },
  },
  requiredFlags: ["shellExecution.unsafe_enabled"],
};

const tests = RuntimeCapabilitiesConformance.buildTests(fixture);
for (const t of tests) it(`[${t.category}] ${t.name}`, t.run);

The suite generates 6 schema tests (3-state manifest validation
across all 5 substrate slots, AgentConnector manifest_unsupported
correctness, etc.) + one test per supplied probe + one coverage
test that fails if any requiredFlags entry has no probe (the
load-bearing close).

3. unknown-llm-arg + unknown-data-read-arg — sibling kwarg lints

Tier-2 warnings sibling to v0.16.4's unknown-llm-model. Catch
provider-API kwargs leaking through the bridge — e.g.
$ llm prompt="..." temperature=0.7 silently dropped by
LocalModelMcpConnector because LocalModel.run() only consumes
{maxTokens, model}. Closed kwarg surfaces:

• $ llm: prompt / maxTokens / model / timeout / approved / fallback
• $ data_read: mode / query / limit / connector / fallback / domain_tags / filters / min_confidence

Same per-rule structure as unknown-llm-model: silent without
context, dedupe by target:kwarg, off-target ops skipped via the
first-token / op.mcpConnector discrimination from v0.16.4.

4. Docs — playbook §Case 2 + onboarding-scaffold + McpConnectorTemplate

• docs/adopter-playbook.md §Case 2 path (b) now points at the
  bundled HttpMcpConnector as the default for Streamable HTTP MCP
  servers; path (c) covers the forked-template case for adopters who
  need behavior the bundled connector doesn't expose.
• examples/onboarding-scaffold/connectors.json includes an
  _example_http_mcp alongside the existing _example_remote_mcp,
  showing both shapes.
• examples/connectors/McpConnectorTemplate/README.md rewrites the
  bundled-impls table to lead with HttpMcpConnector + drops the
  "near-term roadmap" disclaimer.

Internal

• src/connectors/http-mcp.ts — new class + fromConfig factory.
  Registered in KNOWN_CONNECTOR_CLASSES. Re-exported from package
  root + /connectors subpath.
• src/testing/conformance.ts — RuntimeCapabilitiesConformance
  suite + types. Re-exported from /testing.
• src/lint.ts — UNKNOWN_LLM_ARG + UNKNOWN_DATA_READ_ARG rules
  • closed-surface constants. Registered in RULES tier-2 alongside
    v0.16.4's UNKNOWN_LLM_MODEL.
• +19 tests in tests/v0.16.5-http-mcp.test.ts (real local HTTP
  server, exercises full session-handshake + SSE-parsing flow).
• +10 tests in tests/v0.16.5-runtime-capabilities-conformance.test.ts
  (validates the conformance suite itself against bundled bootstrap).
• +11 tests in tests/v0.16.5-sibling-kwarg-lints.test.ts.
• 1484 tests passing (was 1444 at v0.16.4 — 40 new total this ring).

Process notes

Resolved-thread blind spot. v0.16.4 underdelivered against Perry's
934fc9d8 sign-off because that thread was resolved + sibling to the
v0.16.3 ring I was working on — never appeared in my pending-response
mailbox sweep. Banked the refinement to the cold-pickup checkpoint
discipline: query resolved threads addressed to self in the recent
past, scan for forward-looking commitments still owed.

Discipline-only-contracts class count. 12 instances closed since
d0fb1375. v0.16 series alone: 7 (canonicalization /
trust-boundary / parity / bridge-routing / manifest-exposure /
unknown-llm-model / this ring's three closures: HttpMcpConnector
making the "fork or rebuild" gap structural, RuntimeCapabilitiesConformance
making the multi-layer-promise pattern lockstep, sibling kwarg lints
closing the documented-but-unenforced kwarg surface).