fix(reliability): bound rich-clipboard traversal queue before allocation

[seonghobae]

Current authoritative state

Protected shipped truth is exact main@3b38ead2d00f44eb578d0689087b9293b3dabe1e. The original issue statement describing main@e8109ec2a17de8bd6594487aa12c8c8a93cb2c03 materializing/enqueuing a broad node before enforcing maxNodes is historical RCA, not current active-PR behavior.

The former Draft #164 is closed/superseded and must not be revived. Canonical single-writer Draft PR #359 (fix(reliability): preflight clipboard size and traversal budget) now carries the resource-preflight repair on current protected main; current exact Draft head is 1721f10124d93bc4e1a9408cc173b1619c198c42, base main@3b38ead2d00f44eb578d0689087b9293b3dabe1e, mechanically mergeable and still Draft.

Executable contract / TDD lineage

• RED 51f9edfdff7de9072cafa8cebaf068dc39f92208: an ASCII nine-code-unit string under maxHtmlBytes: 8 still reached TextEncoder.prototype.encode, and a three-child fragment under maxNodes: 2 performed three NodeList.item() reads before node_limit_exceeded.
• GREEN 71654a8e59eecd72f2a23ebec173e4e537c927d9: reject sourceHtml.length > maxHtmlBytes before encoding, and reject visited + queued + enqueueable > maxNodes before child materialization. Closed-details summary traversal uses the same queue invariant; hidden/dropped subtrees remain unvisited.
• Current synchronized head 1721f10124d93bc4e1a9408cc173b1619c198c42 preserves source order, exact existing redacted codes/messages, depth checks, semantic allowlist, SafeLink policy, UTF-8 exact checking for in-ceiling non-ASCII input, default/max configuration ceilings, standalone no-service/no-network/no-database/no-credential/no-model behavior, and host error redaction.
• Companion issue fix(reliability): reject obviously oversized rich clipboard HTML before UTF-8 encoding #163 UTF-8 preflight stays on the same fix(reliability): preflight clipboard size and traversal budget #359 lane. Draft fix(security): fail closed on hostile clipboard throw values #351 separately owns hostile thrown-value containment; do not create a competing src/extensions/SafeClipboard.ts writer.

Exact-current-head evidence

For unchanged exact #359 head 1721f10124d93bc4e1a9408cc173b1619c198c42:

• CI 32078914337: completed / success;
• Security Scan 32078914160: completed / success;
• SAST Semgrep 32078914379: completed / success;
• qualifying formal approving reviews: 0;
• unresolved inline review threads: 0.

Repository-local technical success is not qualifying independent approval and does not replace separately applicable central required workflows or then-live governance. Pending, queued, skipped, cancelled, absent, stale, predecessor, status-only or model-only evidence remains non-passing.

Integration boundary

The resource defect is repaired on active Draft #359 but is not protected-main shipped behavior until integration. Keep this issue open and keep #359 Draft/unmerged while #118 owns exact protected v0.6.0 publication/provenance/digest operational acceptance. Refetch exact head/live base, ancestry/mergeability, live governance, formal reviews/threads and every applicable repository/central workflow before any lifecycle transition. Do not transfer #164 or predecessor evidence, self-approve, weaken gates, move protected main, or fabricate release identity.