docs(finality): align flashblock reorg rate with <0.1% target

[youssefea]

What changed? Why?

Closes Base Knowledge Base gap gap-20260924-flashblock-reorg-rate-docs-disagree-vs: "What is the current Flashblock (preconfirmation) reorg rate on Base Mainnet: <0.1% or <0.001%?" (gaps log, DEVREL-859).

Transaction Finality said Flashblocks reorg "less than 0.001% of the time". Throughput and Limits lists the reorg rate as < 0.1%, and the Flashblocks FAQ calls < 0.1% a target. This PR changes the Flashblock Inclusion step in docs/specifications/transactions/transaction-finality.mdx to call < 0.1% a target and link to Throughput and Limits. It does not state an observed Mainnet rate.

Notes to reviewers

• Primary sources (this repo, master):
  • docs/specifications/transactions/throughput-and-limits.mdx, Flashblock Performance table: "Reorg rate | < 0.1%"
  • docs/specifications/flashblocks.mdx, FAQ "How Frequently Do Flashblock Reorgs Happen?": "Base targets a Flashblock reorg rate of < 0.1%"
• Owner confirmation needed before merge (Base Flashblocks/protocol team): please confirm that < 0.1% is the right public figure to present as a target. Also confirm whether the earlier < 0.001% was a measured Mainnet rate that should be published separately, with its definition and measurement window.
• This replaces the Transaction Finality reorg-rate part of docs: sync upgrade, RPC, and node operator pages after Cobalt #2092, which is unmerged. This PR does not include the other changes in docs: sync upgrade, RPC, and node operator pages after Cobalt #2092.

How has it been tested?

• node scripts/lint-mdx.js --files-from=<changed files>: 0 errors, 0 warnings
• node scripts/validate-docs-structure.js: fails only because of a redirect that was already broken (/upgrades/denim/eip-8130 -> missing /specifications/native-account-abstraction). This PR does not cause it.
• The new internal link /specifications/transactions/throughput-and-limits#flashblock-performance resolves: the page is in docs/docs.json and has a ## Flashblock Performance heading.

Screenshots

N/A (text-only change)

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[cb-heimdall]

🟡 Heimdall Review Status

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[linear]

DEVREL-859

[github-actions]

Docs review

Risk: Low (one AI review) · risk: low · shadow mode, not enforced

• small change with no risk signals

Verdict: Fits, with changes · reviewed 65c20d0 with gpt-6-luna

This updates the Flashblock inclusion note on the live Transaction Finality page, which is an appropriate place for the information. The wording presents the figure as a target rather than an observed Mainnet rate, consistent with the supplied facts; add terminal punctuation to the changed sentence.

Suggestions

1. Add terminal punctuation (writing, docs/specifications/transactions/transaction-finality.mdx L28) — suggestion posted inline
   The changed sentence has no ending punctuation. Add a period to make the bullet read as a complete sentence.
   Evidence: The Base writing guidelines call for clear, direct sentences; the neighboring bullet on line 29 ends with a period.

What the reviewer checked

Page	Placement	Index section	Neighbors read
docs/specifications/transactions/transaction-finality.mdx	Live in navigation	not in llms-full.txt	0

Links added: /specifications/transactions/throughput-and-limits#flashblock-performance (live)

Advisory review from the Docs PR review workflow (run). It does not approve, block, or edit this PR. Add the skip-ai-review label to turn it off for this PR.

[github-actions]

Suggested edits from the docs review. Each one is optional; apply it with "Commit suggestion" if you agree.

[github-actions]

Add terminal punctuation

The changed sentence has no ending punctuation. Add a period to make the bullet read as a complete sentence.

Suggested change

	* Base targets a Flashblock reorg rate of less than 0.1%, as listed in [Throughput and Limits](/specifications/transactions/throughput-and-limits#flashblock-performance)
	* Base targets a Flashblock reorg rate of less than 0.1%, as listed in [Throughput and Limits](/specifications/transactions/throughput-and-limits#flashblock-performance).