Upstream sweep 2026-08-06: bump ant-node to 9a50c6b

[JimCollinson]

Metadata-only stamp refresh from the daily upstream sweep. All 11 drifted records are ant-node and classified metadata-only; no prose PR or manual-review issues were opened.

Upstream

• ant-node: db4c851 → 9a50c6b

Source artifacts inspected

• Cargo.toml (release bump 0.16.0 → 0.17.0)
• src/payment/verifier.rs (the only src/ change in the range)
• src/payment/pricing.rs (unchanged in the range; re-exports calculate_price from ant-protocol)
• docs/adr/ADR-0006, docs/adr/ADR-0008, new docs/adr/ADR-0010 upstream

Developer-facing change

Internal refactor; no developer-facing impact. The range is a 0.17.0 release bump plus a receiver-side price floor added to src/payment/verifier.rs that checks a settled payment against the close group's median commitment-bound price. The floor is an internal node-side economic admission mechanism gated behind an environment variable and defaulting to shadow mode (computed and logged, not enforced), so client-facing behaviour is unchanged: quote collection, payment construction, EVM network choices, cost-estimation endpoints, and payment modes all present the same surface. The node-side pricing formula documented on payment-model.md (BASELINE + K × (n / D)^2) lives in ant-protocol, which this range does not touch.

Files changed in this PR

• docs/architecture/system-overview.md
• docs/core-concepts/payment-model.md
• docs/guides/overview.md
• docs/guides/set-up-a-local-network.md
• docs/guides/test-your-application.md
• docs/reference/glossary.md
• docs/reference/source-repositories.md
• docs/rust/embed-a-node-in-your-application.md
• docs/sdk/start-the-local-daemon.md
• skills/start/SKILL.md (frontmatter verified_commits.ant-node + verified_date)
• skills/start/version.json (verified_commits.ant-node)
• planning/sweeps/2026-08-06.md (new summary)

Verification run

• Envelope check: only source_commit/verified_date lines, the verified_commits.ant-node values, and the new sweep summary changed. No prose, no scripts/, .github/, registries, version, published_date, CHANGELOG.md, or frontmatter version: moved. No target-manifest block touched.
• python3 scripts/sweep_poll.py re-run on this branch: status: "ok", 0 drifted records, ant-node fully resolved.
• version.json parses as JSON; SKILL.md frontmatter parses as YAML.
• src/payment/pricing.rs re-grep against the pinned 9a50c6b checkout: the calculate_price formula backing payment-model.md is unchanged and lives in ant-protocol.
• markdownlint / link checkers: skipped — not configured in this repo.

Uncertainties

The new receiver-side price floor is merged but defaults to shadow mode, so it is treated as an internal mechanism and not documented. If a reviewer wants the group-median price floor surfaced on payment-model.md ahead of enforcement being enabled by default, that would be a separate prose change.

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