fix: make async scanner polling resilient to transient errors

[netomi]

Problem

Some Argus scans were recorded as External scan failed (no details from scanner) although Argus completed them successfully. Two causes in the poll path:

• One poll response with status: error (mapped to FAILED) was terminal. A scanner that reports a transient error and then recovers still failed the scan.
• HttpClientExecutor returns the body of any 4xx response as a success, so a 4xx JSON error body could be read as a scan status.
• A poll that threw (for example a 502) was only retried by JobRunr's short backoff. The next poll is scheduled only after a successful poll, so a longer outage ended the polling chain until the scanner timeout failed the job.

The "no details" text comes from fetchErrorDetail calling the result endpoint, which is the same URL as poll and returns a body with no matches.

Changes

• HttpClientExecutor: every non-2xx response (including 3xx) is an error, for start, poll and result calls. The 4xx body pass-through is removed, since it is no longer needed and let an error body be read as a scan status.
• ScannerPollHandler: a ScannerException during polling is recorded on the job and the next poll is scheduled. It counts towards max-attempts.
• ScanAPI: a scanner job exposes errorMessage only once terminal, so the transient marker is not shown.
• ScannerPollHandler: FAILED must be seen on two consecutive polls before the job fails. The first sighting is stored as a marker in ScannerJob.errorMessage, which avoids a schema change. Any other status clears it.
• RemoteScanner: the truncated raw response is logged at WARN when a poll maps to FAILED.

Tests

• ScannerPollHandlerTest: first error not final, second consecutive error final, recovery clears the marker, poll exception reschedules.
• HttpClientExecutorTest: 4xx and 3xx responses with a body throw.
• ./gradlew test --tests 'org.eclipse.openvsx.scanning.*' passes except 4 recovery-lock tests that need Testcontainers, which could not start here. spotlessCheck is clean.

Notes

A real failure is now detected one poll interval later (15s for Argus).

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

Strict mode misses 3xx responses, and the internal failure marker leaks through the admin API.

2 open findings

• Strict mode accepts non-followed 3xx responses · New
• Internal scanner error marker leaks through admin API · New

What changed in this PR

Improves resilience of asynchronous scanner polling during transient failures.

Changes:

• Adds strict HTTP status handling for polling.
• Retries poll exceptions and confirms consecutive failure statuses.
• Adds regression tests for polling and HTTP behavior.

File	Description
ScannerPollHandler.java	Reschedules failed polls and confirms scanner failures.
RemoteScanner.java	Uses strict polling requests and logs failed responses.
HttpClientExecutor.java	Adds configurable strict response handling.
ScannerPollHandlerTest.java	Tests polling recovery and failure confirmation.
HttpClientExecutorTest.java	Tests strict and lenient 4xx handling.

🧠 Review effort: Balanced

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[Copilot]

🟢 Approval recommended

The previously identified issues are resolved with focused regression coverage.

0 open findings

2 resolved since last review

• Internal scanner error marker leaks through admin API
• Strict mode accepts non-followed 3xx responses

🧠 Review effort: Balanced

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[Copilot]

🟡 Changes recommended

Redirect-following remains enabled, allowing some 3xx scanner responses to bypass the new validation.

1 open finding

• Disable redirect following to enforce non-2xx response checks · New

🧠 Review effort: Balanced

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[Copilot]

🟢 Approval recommended

The changes address the reported failure modes with focused regression coverage and no unresolved issues.

0 open findings

1 resolved since last review

• Disable redirect following to enforce non-2xx response checks

🧠 Review effort: Balanced

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