Close first librarian promote round-trip + add --accept flag

scripts/librarian_promote.py gains a --accept flag that copies the
generated draft to the suggested docs/research/ target in the same
invocation. This is explicit per-invocation opt-in, not auto-apply:
the operator types --accept knowingly, the cp is still a deliberate
acceptance decision, just expressed in one command instead of two.

docs/research/option-a-bench-result.md is the first promoted note,
generated by gemini from
docs/archive/option-a-bench-result-2026-05-07.md and accepted
verbatim. Spot-check verified that cited file:line locations match
current source (traversal.pyx:473-475 and
inference_server.py:226-228 carry the cited code), the Last-verified
header reflects today's date and HEAD, and the durable conclusion
(sync-blocking policy boundary as the structural ceiling, not IPC
plumbing) is preserved.

This closes the end-to-end loop the librarian was designed for:
oversize check surfaced docs/performance.md, the routing pass split
durable analysis into the archive entry, the promote dispatcher
turned the archive entry into a research draft, and the human
accept step landed it as a tracked research note. Took one LLM call.

Removes the now-resolved ignore-list entry for
docs/research/option-a-bench-result.md (the file exists; the
forward reference is real).

scripts/librarian.sh exits 0 against the working tree.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/librarian-ignore.txt

@@ -18,8 +18,3 @@ scripts/run_model_size_experiment.sh
 
 # Future config described in docs/plans/torch_compile.md
 configs/deep_cfr/default_compile.yaml
-
-# Hypothetical accept target named in docs/plans/librarian.md as a
-# smoke-test illustration; resolves naturally if Stage 2 promote is
-# accepted, otherwise stays a forward reference.
-docs/research/option-a-bench-result.md

scripts/librarian_promote.py

@@ -24,6 +24,7 @@ from __future__ import annotations
 import argparse
 import os
 import re
+import shutil
 import subprocess
 import sys
 from datetime import datetime
@@ -32,7 +33,7 @@ from pathlib import Path
 LLM_COMMANDS = {
     "claude": ["claude", "-p"],
     "codex": ["codex", "exec"],
-    "gemini": ["gemini", "-p"],
+    "gemini": ["gemini", "-p", ""],
 }
 
 DATE_SUFFIX = re.compile(r"-\d{4}-\d{2}-\d{2}$")
@@ -85,6 +86,16 @@ def main() -> int:
         action="store_true",
         help="Print the assembled prompt to stdout and exit; do not call the LLM.",
     )
+    parser.add_argument(
+        "--accept",
+        action="store_true",
+        help=(
+            "After the draft lands in runs/tmp/, also copy it verbatim to the "
+            "suggested docs/research/ target. Explicit per-invocation opt-in: "
+            "still propose-only by design (you are choosing acceptance "
+            "knowingly), not auto-apply."
+        ),
+    )
     args = parser.parse_args()
 
     root = _repo_root()
@@ -145,7 +156,8 @@ def main() -> int:
         file=sys.stderr,
     )
     result = subprocess.run(
-        cmd + [prompt],
+        cmd,
+        input=prompt,
         capture_output=True,
         text=True,
         check=False,
@@ -157,10 +169,23 @@ def main() -> int:
 
     draft_path.write_text(result.stdout, encoding="utf-8")
     print(f"Draft written to: {draft_path.relative_to(root)}")
-    print(f"Suggested target on accept: {rel_target}")
-    print()
-    print("Next: review the draft. To accept verbatim:")
-    print(f"  cp {draft_path.relative_to(root)} {rel_target}")
+
+    if args.accept:
+        if target.exists():
+            print(
+                f"Refusing --accept: {rel_target} appeared while the LLM ran.",
+                file=sys.stderr,
+            )
+            return 1
+        shutil.copyfile(draft_path, target)
+        print(f"Copied to: {rel_target}")
+        print("Next: review the diff and `git add` + commit if you're satisfied.")
+    else:
+        print(f"Suggested target on accept: {rel_target}")
+        print()
+        print("Next: review the draft. To accept verbatim:")
+        print(f"  cp {draft_path.relative_to(root)} {rel_target}")
+        print("Or rerun with --accept to copy in the same step.")
     return 0