[afourniernv]

Summary

Record bounded credential-preparation and withholding outcomes on the inspected
request, without exporting secrets. This is layer 3/6, based on
middleware #9.
The HTTP core remains NVIDIA #5214.

Related Issue

Closes NVIDIA#5395. Tracking: NVIDIA#5210.
This remains a draft on the author fork, not upstream promotion.

Changes

• Enrich the existing operation-owned credential stages for static headers,
  buffered bodies, signing and token grants, including Current/DUPLEX hooks.
• Keep preparation separate from accepted upstream writes and target delivery.
• Preserve endpoint/placement checks, generation fencing and pre-injection
  request-header custody. Protected Authorization headers remain protected.
• Compute the effective outcome without cloning a complete metadata snapshot.
• Export mechanism, placement and outcome, never credential values, claims or
  exchange bodies. Preflight rejection does not manufacture a preparation span.

No new configuration, gateway RPC, protobuf or public result fields.
The stack incorporates main f37687a2d, including the new HTTP hooks (NVIDIA#4359).

Testing

• Network: 1,726 passed; two existing ignored.
• Supporting suites: middleware 166, OCSF 187, OpenTelemetry 70 passed.
• Total: 2,149 passed. Current/DUPLEX and both accepted-write tracking modes
  are covered, including late-header protection and typed signing failures.
• Strict all-target Clippy, full pre-commit and the normal commit hook passed.
• Signed integration update: 0f9452c73; parents 312287243 and 5dd065926.
• Final integrated stack 6b81f8784: full mise run test passed unchanged
  (9,189 Rust tests, 94 auxiliary tests, Python 211 and TypeScript 206).
• Ten live native Hermes/Relay workflows used matching-source binaries,
  protected synthetic services and authenticated read-only GitHub. Verified
  preparation stages, selected resource identities and absence of actual
  credential values in captured telemetry. All 45 receipts joined OCSF.

Live validation is cumulative on the final stack, not isolated-layer E2E.
Initial fixture failures and incomplete agent attempts are retained; isolated
and final full reruns passed. Full repository mise run ci is not claimed.

Checklist

• Existing review history retained; no force push.
• Final pre-commit and signed integration commit.
• Relevant crate and published observability documentation retained.
• Fresh final-stack live validation.
• Upstream promotion after earlier layers.