Fix/visualise path segments

[milesAraya]

Content

Summary

• The Visualize panel never showed the "Visualization data deleted" message when an experiment's intermediate data had been deleted by the expiration lifecycle job. Plots continued to render even when has_intermediates was false in the database.
• Root cause: getExperimentUidFromFilePath() extracted the wrong path segment (segments[2], the function node ID) instead of the experiment UID (segments[1]). The selector always returned true (default for unknown UID), so the degradation guard never triggered.
• Added unit tests for getExperimentUidFromFilePath() covering all output path formats and edge cases.

Design Decisions

• segments[1] not segments[2] -- Output paths from the backend are normalized to {workspaceId}/{experimentUid}/{functionNodeId}/filename by normalize_output_path(). The original comment incorrectly described the format as having a prepended nodeId. Verified by inspecting actual API responses across all algorithm types (Suite2P, CaImAn, LCCD, PCA, CCA, LDA) and tutorial experiments.
• Exported the function -- getExperimentUidFromFilePath was module-private. Exported it so the test file can import it directly without rendering the full React component.

Evidence

The bug: The original code extracted segments[2] from the file path, based on an incorrect comment:

// BEFORE (wrong):
// Path format: "{nodeId}/{workspaceId}/{uniqueId}/{nodeId}/filename"
return segments.length >= 3 ? segments[2] : ""

Actual path format from live API response (GET /experiments/8):

8/a5feff3e/cca_e9mbfm8vck/coef.json
│ │          │
│ │          └─ segments[2] = "cca_e9mbfm8vck" (function node ID -- WRONG)
│ └─ segments[1] = "a5feff3e" (experiment UID -- CORRECT)
└─ segments[0] = "8" (workspace ID)

Because segments[2] returned a function node ID (e.g. cca_e9mbfm8vck), the selector selectExperimentHasIntermediates("cca_e9mbfm8vck") never found a matching experiment and defaulted to true via ?? true, bypassing the guard entirely.

Live verification on development environment:

• Set has_intermediates = 0 on experiment a5feff3e in workspace 8
• Experiment table correctly showed grayed-out name with tooltip: "Visualization data deleted due to subscription expiration. NWB download and reproduce still available."
• Visualize panel still rendered plots (bug confirmed -- the guard in DisplayDataItem.tsx was ineffective)

References

• Related to PR Refactor ConfigReader/Writer #380 (expired subscription data deletion policy)
• REPORT_2.md -- full test report documenting the bug discovery

Files changed

• frontend/src/components/Workspace/Visualize/DisplayDataItem.tsx -- Fix path segment index from segments[2] to segments[1]; correct the path format comment; export getExperimentUidFromFilePath for testability
• frontend/src/components/Workspace/Visualize/__tests__/DisplayDataItem.test.ts -- New: 7 tests covering standard output paths, timeseries, tiff subdirectories, and null/empty/single-segment edge cases

Manual Testcases

1. Set has_intermediates = 0 on an experiment record in the database
2. Navigate to the Visualize tab for that experiment
3. Select any visualization output (e.g. a plot from CCA, Suite2P ROI, etc.)
4. Verify the panel shows "Visualization data deleted due to subscription expiration." instead of the plot
5. Revert the flag (has_intermediates = 1) and refresh -- plots should render normally
6. Run frontend tests in Docker:

   npx jest --testPathPattern="DisplayDataItem" --passWithNoTests
   

   Expected: 7 tests pass

Unit, Integration, Contract Test Coverage

• DisplayDataItem.test.ts -- 7 unit tests: standard output path, timeseries path, tiff subdirectory path, null input, undefined input, empty string, single-segment path

Others

Difficulties

• The bug was not caught by existing tests because DisplayDataItem had no test coverage and the function was not exported. The incorrect path comment made it appear intentional.

Risk Assessment

Area	Risk	Notes
Visualize panel degradation	Low	Only affects display when has_intermediates is false; no change to data serving or other UI states
Path extraction logic	Low	All backend output paths go through normalize_output_path() which guarantees {workspaceId}/{uid}/... format; verified across all algorithm types
Export of getExperimentUidFromFilePath	Low	Pure function with no side effects; export only adds test access