[JasonColapietro]

Summary

• replace removed mpp-sdk paths with the current Pay Kit Rust, TypeScript, and harness locations
• route x402 exact, upto, and batch-settlement work to the public in-repo implementations instead of a private checkout
• update MPP subscription from unpublished/future guidance to the shipped Rust and TypeScript sources
• make protocol scope target-language-specific and require current harness evidence before marking a matrix cell complete

Why

The official payment-sdk-implementation skill described x402 as future, said subscriptions had no implementation, and directed contributors to removed paths and a private local checkout. Following it would block valid ports or cause work against the wrong source tree.

Verification

• strict YAML frontmatter parse; description is 327 characters
• every newly cited in-repo source, test, IDL, workflow, and harness path resolves
• stale-path/status scan found no mpp-sdk root, rust/crates/mpp path, private checkout, or scaffold-only instruction
• git diff --check

The generic quick_validate.py helper was also attempted, but its local Python environment does not include PyYAML; the equivalent metadata checks above passed.

[greptile-apps]

Greptile Summary

The PR modernizes the Pay Kit implementation skill so contributors use current public Rust, TypeScript, protocol, and harness references.

• Replaces removed SDK paths and private-checkout guidance with current in-repository locations.
• Updates x402 and MPP subscription status and porting guidance to reflect shipped implementations.
• Makes protocol scope language-specific and requires matching harness evidence before claiming compatibility.
• Corrects the focused harness guidance by distinguishing x402 adapter selectors from intent/scenario selectors and explicitly documenting the unsupported batch-settlement selector.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains; the previously reported batch-settlement selector issue is addressed by accurately documenting its current rejection and the prerequisite harness work.

Important Files Changed

Filename	Overview
skills/pay-sdk-implementation/SKILL.md	Updates the skill’s scope, protocol matrix, source references, and harness workflow to match the current repository.
skills/pay-sdk-implementation/references/harness.md	Documents current MPP and x402 harness selectors and correctly warns that batch settlement needs harness support before validation.
skills/pay-sdk-implementation/references/intents/x402-batch-settlement.md	Replaces speculative private-source guidance with public implementation references and explicit harness prerequisites.
skills/pay-sdk-implementation/references/intents/mpp-subscription.md	Replaces obsolete unpublished-intent guidance with current Rust and TypeScript implementation sources.
skills/pay-sdk-implementation/references/repo-layout.md	Updates repository layout and canonical Rust source locations to the current Pay Kit structure.

_{Reviews (2): Last reviewed commit: "docs(skill): bound x402 harness selector..." | Re-trigger Greptile}

[greptile-apps]

Batch selector is rejected

When a contributor applies the documented x402-<scheme> pattern to the advertised batch-settlement cell, the resulting MPP_HARNESS_INTENTS=x402-batch-settlement value is rejected by the current harness, preventing the required compatibility validation from running.

Suggested change

	For x402, use the corresponding `X402_HARNESS_CLIENTS` and
	`X402_HARNESS_SERVERS` selectors plus `MPP_HARNESS_INTENTS=x402-<scheme>` and a
	matching `MPP_HARNESS_SCENARIOS` value. Copy a current command from the target
	scheme's entries or README; do not assume the MPP adapter IDs also implement
	x402.
	For x402 schemes currently supported by the harness, use the corresponding
	`X402_HARNESS_CLIENTS` and `X402_HARNESS_SERVERS` selectors plus a supported
	`MPP_HARNESS_INTENTS` value (`x402-exact` or `x402-upto`) and a matching
	`MPP_HARNESS_SCENARIOS` value. Copy a current command from the target scheme's
	entries or README; batch settlement requires adding a harness intent and
	scenarios first. Do not assume the MPP adapter IDs also implement x402.

Knowledge Base Used: Cross-language conformance harness

[lgalabru]

LGTM, thanks @JasonColapietro!