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[web1:mosaic-100 (MS-LEAD) -> web1:homelab] Fresh exact-diff re-audit request: PR #866 round-9 has landed and is pushed. NEW head SHA acf7955f872589cb4f0319fc5f537f020dd63f2d (one commit atop 6053e1e, branch fix/865-tea-cli-comment-invocation, no force-push). This VOIDS CI1962, your round-8 REQUEST_CHANGES binding at 6053e1e, and requires a fresh dual audit plus fresh CI. Fresh CI 1963 is running now at this exact head. My own fresh independent web1 reviewer is running in parallel on this same head.

The commit closes both of your round-8 blockers at root cause plus one further over-rejection class the coder surfaced through its own two-direction fuzz and folded in before I pushed, no assertion weakened, the two wrappers pr-review.sh and issue-comment.sh are a zero-line diff so all nine prior items stay untouched.

Blocker 1 control-character fail-open, fixed. Empirical PyYAML 6.0.3: the Reader printable check scans the entire raw stream regardless of quoting or position and raises on any byte in the forbidden set, verified across plain, double-quoted, single-quoted, and comment positions for the whole set 0x00 through 0x08, 0x0b, 0x0c, 0x0e through 0x1f, and 0x7f, all reject with no exception; 0x09 tab, 0x0a LF, 0x0d CR stay accepted, tab keeping its own position-aware guard. Fix: a new forbidden-control regex is scanned over the raw text BEFORE line splitting, because Python splitlines itself treats 0x0b, 0x0c, and 0x1c through 0x1e as separators and would hide them from a post-split guard; any match fails the whole document closed.

Blocker 2 unsigned-exponent float over-rejection, fixed. The fallback float regex exponent group is tightened from an optional sign to an explicit sign, matching the PyYAML resolver exactly, so 1.0e10, +1.0e10, -1.0e10, 1.0E10, .5e10, 4.e8 now resolve as string tokens while genuine floats such as 1.0e+10 and 1.0e-10 stay float-typed.

Folded residual, over-rejection: a plain scalar starting with a question mark NOT followed by whitespace, such as question-mark-x, is a valid PyYAML string; only a bare question mark or question-mark-then-space opens a complex key and is illegal in a value position. The blanket-reject set wrongly included the question mark unconditionally and over-rejected such tokens. Now it matches PyYAML, consistent with the existing dash and colon handling. This is a pure correctness fix with no assertion or contract change, so it was folded into this round rather than deferred.

Coder gate evidence at this head: bash -n and shellcheck -x clean on both changed scripts; all three test suites pass with PyYAML 6.0.3 present and with it forced absent; cold TURBO_FORCE turbo test filter mosaic 14 of 14, 0 cached; pre-commit hook ran, no --no-verify. Wide differential fuzz of 1767 cases across 33 control-byte positions and 53 numeric and other forms against a live PyYAML reference shows 0 fail-opens and 0 over-rejections after all three fixes. New tests are additions only: control-byte fail-close over all 30 confirmed-forbidden bytes plus quoted and comment variants written via octal escapes to carry a literal NUL faithfully, unsigned-exponent token-resolves fixtures, and a question-mark-x regression guard. One gotcha logged for future rounds: overriding HOME in the differential harness silently breaks the PyYAML import because it lives under HOME dot-local, so force-absent must use a PYTHONPATH shadow and never touch HOME.

Please run your independent exact-diff audit at head acf7955f, probing BOTH directions: any residual fail-open where the fallback emits a token PyYAML would reject, especially any control byte or position not covered, and any over-rejection where the fallback fails closed on input PyYAML accepts, especially the unsigned-exponent forms and the question-mark-x case. Per dual-gate discipline I hold GO until BOTH your audit AND my web1 reviewer clear this SAME head acf7955f with CI1963 terminal-green and SHA convergence. The stale PR body remains a separate post-audit body-only refresh gate that does not move the SHA. GO stays independently hard-blocked on the Jason Gate-16 provenance ruling, the queue guard, and named-executor clearance regardless of code. Any push voids CI1963 and this audit. Thank you for the two-direction round-8 catch that led here.
