fix(ENGKNOW-3566): fail loud on MDR file lookup resolution failure

[gmagnu]

Problem

ENGKNOW-3566 — a .gord dictionary lookup over MDR-backed sources could silently fail. A single unresolvable MDR document yielded a degenerate zero-row header (the raw mdr://…cram?env=prd URL as a data value) instead of an error; with two tags it surfaced only as a confusing "header mismatch" error.

gor source/bam/bam.gord -f A,B | top 10   # header mismatch error
gor source/bam/bam.gord -f A   | top 10   # works
gor source/bam/bam.gord -f B   | top 10   # bogus header, zero rows, NO error

Root cause

Three silent-failure holes in MdrServer.java:

1. cacheMdrUrls — catch (Throwable e) {} swallowed every error (auth, outage, bad response), nothing logged.
2. cacheMdrUrls — s.file = u.url() assigned even when the resolved url was null/blank, corrupting the source into a garbage path.
3. getMdrDocument/resolveMdrUrl — never checked the resolved url was non-blank, so a blank url flowed downstream and was opened as a bogus file.

Fix — fail loud

Invariant: an mdr:// source resolves to a real, non-blank URL, or the query throws a clear GorResourceException. No blank/unresolved url reaches a reader, no MDR error is swallowed without at least a log record.

• New pure, network-free validateResolved(MdrUrlsResult, URI) — throws on null result, urls().size() != 1, or null/blank url. getMdrDocument routes through it.
• resolveMdrUrl guards its return against a blank cached url.
• cacheMdrUrls skips caching/rewrite on a blank resolved url (leaves mdr:// for per-source resolution) and logs bulk-cache failures at WARN instead of swallowing. Bulk caching stays best-effort by design — per-source read now fails loud.

Scope confined to MdrServer.java. Exact stg-side reason a document resolves blank is a separate deferred root-cause follow-up.

Tests

New plain unit test UTestMdrServer (no Keycloak/network, not @Ignored): 7 cases covering valid url, null/blank url (regression), null result, null urls list, zero/multiple urls. Full :model:test — 1488 pass, no regression.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR tightens MDR-backed mdr:// source resolution in the model driver layer so MDR lookup failures can’t silently degrade into bogus/blank resolved paths; instead, resolution now consistently throws a clear GorResourceException. This aligns MDR resolution behavior with the expectation that dictionary lookups either resolve to a real URL or fail loudly at read time.

Changes:

• Add MdrServer.validateResolved(...) to enforce “exactly one, non-blank URL” invariants for MDR responses, and route per-document resolution through it.
• Harden resolveMdrUrl and cacheMdrUrls to avoid propagating/caching blank URLs and to warn-log bulk-cache failures instead of swallowing them.
• Add UTestMdrServer unit tests covering null/blank URL and malformed MDR response shapes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
model/src/main/java/org/gorpipe/gor/driver/providers/stream/sources/mdr/MdrServer.java	Enforces non-blank resolved MDR URLs, logs bulk resolution failures, and prevents blank URL caching/rewrite.
model/src/test/java/org/gorpipe/gor/driver/providers/mdr/UTestMdrServer.java	Adds focused unit tests for validateResolved invariants and regression cases.

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[github-actions]

Junit Tests - Summary

4 747 tests  +11   4 569 ✅ +11   18m 58s ⏱️ -20s
  489 suites + 1     178 💤 ± 0 
  489 files   + 1       0 ❌ ± 0 

Results for commit 7dd28d6. ± Comparison against base commit fc81c83.

♻️ This comment has been updated with latest results.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.