docs: Tool-result-only Responses input shipped in v1.12.0; the docs note still says main after v1.11.0

[github-actions]

What this PR does

With the released SMG v1.12.0, does /v1/responses accept an input array containing only function_call_output items (no message item), or is that still unreleased main-only behavior with v1.11.0's 400 'Input items must contain at least one message' as the released contract, as the Input Formats note says?

Why we need it

Source change: smg-project/smg@538ec73

Documentation targets the pinned published stable release.

Commit 115 (smg#2723, 538ec73e, 2026-10-02; diff read in full) removed the input_missing_user_message cross-parameter check from crates/protocols/src/responses.rs (validate_responses_cross_parameters), and it is a first-parent ancestor of the pinned v1.12.0 release. Verified in the release checkout: the check and its 'Input items must contain at least one message' error are absent from the protocols crate (a repo-wide grep finds that message only in the unrelated gRPC conversions path and tests), so a v1.12.0 gateway accepts a tool-result-only continuation. Stale doc, the only place carrying this framing (repo-wide greps for '2723', 'without any message'): src/lib/content/reference/api/responses.md:186-189 'Accepting an input array without any message is new on main after v1.11.0 (smg-project/smg#2723). v1.11.0 and earlier reject such an array with 400...' — under the v1.12.0 pin this labels released behavior as unreleased current-main, so a v1.12.0 operator concludes their release still requires a message item. Required edit: state the acceptance as released v1.12.0 behavior and keep the v1.11.0-and-earlier 400 as the anchored historical caveat, consistent with the same page's already-correct :73 ('In v1.11.0 and earlier an array must also contain at least one message'); the surrounding contract prose (:177-184, Harmony call_id matching) was re-verified by merged #102 and stays. The adjacent :102-107 'new on main after v1.12.0' validation note describes genuinely post-v1.12.0 commits and must not be touched. One independent concern: one commit's released availability, re-anchored in the one note that frames it — the same release-anchor follow-up pattern as merged #170 (rate-limiting FIFO) and #171 (SGLang over ZMQ). Dedup: merged #102 (responses-api:tool-result-only-continuation-accepted, same source commit) documented the behavior correctly as main-only under the earlier v1.11.0 pin and this follow-up does not repeat its content; no other open or closed PR mentions #2723; no open PR holds responses.md. Sentence-level edit, far under 999 lines.

Scope: responses-api / tool-result-only-continuation-release-anchor. Other concerns are deferred.

How to test

• Passed the documentation path and size guard (under 1000 added plus deleted lines; no file-count limit).
• Passed an independent accuracy and single-concern review.
• Passed git diff --check and pnpm check and the production pnpm build.

Checklist

• Tests added/updated (if applicable)
• Docs updated (if applicable)
• Commit includes a DCO sign-off

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[github-actions]

Documentation maintenance: ready. Unsuccessful content rounds: 0/3. Operational attempts: 0/3.

Head: e709199d032a93dc80849dbccabf513b2ef9d935; reviewed main: 105d7201ae6dd49f23bb2f0c7e490505f6ccc54a.
Reviewed SMG source: dcc5cb0b8f2a64694938c10f02c6caaa0c40d5ef.

Single sentence-level edit serving exactly the scoped concern (release anchor for tool-result-only continuation acceptance). Verified in the pinned v1.12.0 checkout (HEAD dcc5cb0b): validate_responses_cross_parameters (crates/protocols/src/responses.rs:3489-3520) lacks the input_missing_user_message check and contains commit 538ec73e's exact replacement comment, proving the acceptance shipped in v1.12.0; the error string 'Input items must contain at least one message' is absent repo-wide. The similar 'Request must contain at least one message' check in the regular gRPC conversions path (conversions.rs:244-246) counts Tool messages produced from function_call_output items (conversions.rs:150-152), so it does not contradict the claim. Retained claims verified: Harmony 'No function call found for call_id' at harmony/builder.rs:846; the quoted v1.11.0 rejection matches the removed code in the source patch (readable historical evidence, previously documented under the v1.11.0 pin by merged #102). Placement: canonical page corrected in place, release note kept as its own short paragraph, the smg#2723 code-change reference removed from prose, no new page, 7 changed lines. Consistency: responses.md:73 table row already agrees; the adjacent post-v1.12.0 validation note is untouched; greps show no other docs page covers this behavior. Limitations: git ancestry could not be traversed with read-only tools (release inclusion established via checkout contents), and the v1.12.0 boundary assumes no intermediate v1.11.x patch release shipped the change. No feedback threads exist on this PR.

Workflow evidence

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