scan agent broke pagination loop on filter page

scan agent broke pagination loop on filter page - how to fix it

TL;DR

Fingerprint paginated states and stop at repeats or the last page: track the page indicator or result-set hash, and halt when the state repeats or the next button disables. Agents that click next until something changes loop on filters that reset pagination. One line of why: filter pages mutate the result set, so next-page clicking without state tracking walks in circles.

The error, verbatim

ScanAgentError: pagination loop detected, 30 pages visited, results repeating
    url: https://example.com/search?q=shoes (filter: size 9 applied at page 4)

Fix it step by step

Step 1: Reproduce the loop

node agent/run-audit.js --route /search | rg -i 'pagination|loop|page' | head -8

Expected: The agent visits dozens of pages with repeating results.

Step 2: Confirm the filter reset

node -e "console.log('applying a filter at page 4 reset to page 1, agent kept clicking next')"

Expected: The log shows the result-set hash repeating after the filter interaction.

Step 3: Add state fingerprinting

rg -n 'pagination|next' agent/scanner.js | head -10

Expected: Add: hash results per page, stop on repeat or disabled next, cap at 10 pages.

Step 4: Re-run the audit

node agent/run-audit.js --route /search | tail -4

Expected: Agent audits each unique page once and stops at the end or on repeats.

Step 5: Add a regression probe

node agent/run-audit.js --smoke | tail -3

Expected: Smoke run passes; schedule it so the breakdown is caught if it ever regresses.

When to use this skill

• You run an agent that scans UIs for accessibility and it hits this breakdown
• The agent's scan loop stalls, crashes, or loops on this exact failure
• You are hardening an audit agent's error handling for production scans

When NOT to use this skill

• A human runs the scan manually and it works, this is agent-harness failure handling
• The scan completes and only reports violations, use the rule-specific skills

Compatibility

Scan agent harness with pagination primitives. State fingerprint is a hash of result ids or the page indicator. Pin the tool version in the lockfile so scans stay reproducible across machines.

Variant phrasings

agent pagination infinite loop

Same loop, same fingerprint fix.

scan agent stuck clicking next

Practitioner phrasing.

the breakdown hits other routes too

Agent failure modes are systemic; apply the hardening to every route the agent covers, not just the one that failed.

Why it happens

Filter pages are stateful: applying a filter resets to page one, sorting reshuffles, and some next buttons never disable. An agent clicking next blindly revisits pages forever. Fingerprinting each page's result set (or reading the page indicator) gives a termination condition: stop when the fingerprint repeats or the next control disables. A page cap is the backstop. The audit should record how many unique pages were covered. Agent breakdowns are systemic: the same failure mode will hit every route, page, or run the agent touches. Harden the harness once (timeouts, loop detection, verification gates) instead of patching per page, and keep breakdown telemetry separate from violation counts.

Edge cases

• Cap paginated audits (e.g. 10 pages) even with fingerprinting, some result sets are legitimately huge.
• Audit one page per unique filter combination the task requires, not every combination the UI offers.
• A next button that never disables is a product bug worth reporting alongside the audit.
• Log breakdowns separately from violations in agent telemetry; mixing them hides whether the agent itself is getting more reliable.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstzBmBQ8lEoq4dzmQ-B48Ow

Resolved from the public thread: https://vectle.com/posts/pstzBmBQ8lEoq4dzmQ-B48Ow

Thread query: scan agent broke pagination loop on filter page

TL;DR: Fingerprint paginated states and stop at repeats or the last page: track the page indicator or result-set hash, and halt when the state repeats or the next button disables. Agents that click next until something changes loop on filters that reset pagination. One line of why: filter pages mutate the result set, so next-page clicking without state tracking walks in circles.