/llms.txt revalidates on every read, so its "Running … at <commit>" line is never an hour stale after a deploy #8470

/llms.txt now answers cache-control: private, no-cache on both the 200 and the 304, so a client revalidates on every read instead of holding an old "Running … at <commit>" line for up to an hour. The fix is in src/web/standards.ts.

• The 200: it previously sent the shared public, max-age=3600 default. It now sets private, no-cache explicitly.
• The 304: an If-None-Match with the current ETag still answers 304. The 304 keeps Vary: Cookie, Authorization, and the test checks x-content-type-options on it.
• ETag: it is a hash of the body, so it changes when the running commit changes. A new test sets two FORGE_APP_COMMIT values and checks the ETag differs and the old one gets a 200 with the new commit line.
• Tests: the existing ETag/304 test now asserts the header on 200 and 304, and fails against max-age=3600.

test/standards.test.ts and test/cache-private.test.ts pass, tsc --noEmit is clean, and scripts/gate.ts printed nothing.

I chose private, no-cache over public, max-age=0, must-revalidate. The body differs for signed-in callers, so a shared cache should not keep it. The cost is that a shared cache can no longer serve the anonymous copy.

I left /sitemap.xml and the other standards files on their one-hour cache, since the issue covers only /llms.txt.

Closes #8464

/llms.txt now answers cache-control: private, no-cache on both the 200 and the 304, so a client revalidates on every read instead of holding an old "Running … at <commit>" line for up to an hour. The fix is in src/web/standards.ts.

• The 200: it previously sent the shared public, max-age=3600 default. It now sets private, no-cache explicitly.
• The 304: an If-None-Match with the current ETag still answers 304. The 304 keeps Vary: Cookie, Authorization, and the test checks x-content-type-options on it.
• ETag: it is a hash of the body, so it changes when the running commit changes. A new test sets two FORGE_APP_COMMIT values and checks the ETag differs and the old one gets a 200 with the new commit line.
• Tests: the existing ETag/304 test now asserts the header on 200 and 304, and fails against max-age=3600.

test/standards.test.ts and test/cache-private.test.ts pass, tsc --noEmit is clean, and scripts/gate.ts printed nothing.

I chose private, no-cache over public, max-age=0, must-revalidate. The body differs for signed-in callers, so a shared cache should not keep it. The cost is that a shared cache can no longer serve the anonymous copy.

I left /sitemap.xml and the other standards files on their one-hour cache, since the issue covers only /llms.txt.

/llms.txt now sends Cache-Control: private, no-cache for a signed-in reader, so it revalidates on every read. The running-commit line is therefore never stale. That is the change from #8464.

The failing check was a test that still expected the old max-age header. The new header is intended, so I fixed the test, not the code. The assertion in test/llms-tools.test.ts:42 now expects no-cache.

test/llms-tools.test.ts and test/standards.test.ts pass (25 tests), and tsc --noEmit is clean. I didn't run scripts/gate.ts or the full suite; the forge's check runs the full suite on this push.

To try it, fetch /llms.txt with a bearer token and read the cache-control header.

Left #8464 open: 3 unticked items remain (/llms.txt answers cache-control: private, no-cache (or public, max-age=0, must-revalidate with the Vary kept) on both the 200 and the 304; an If-None-Match with the current ETag still answers 304.; When the running commit changes, the ETag changes (it is a hash of the body, which carries the line; a test proves it with two FORGE_APP_COMMIT values).; A test asserts the header on 200 and 304 and fails on today's max-age=3600.).