Ndvi Lst Tvdi Single Date Threshold Exceedance

Rules

• Use exact parameter names only: dir_path, ndvi_path, lst_path, output_path, image_paths, threshold.
• Treat EVI like NDVI for this skill; if the tool schema uses ndvi_path, pass the single discovered vegetation raster there.
• When prompt wording conflicts with actual benchmark files, prefer the discovered files over the prompt text unless multiple plausible pairs exist.
• The discovered filename date is authoritative for output_path, downstream references, and final narration.
• Always request a benchmark-relative output_path in compute_tvdi: <question_folder>/tvdi_<discovered-date>.tif.
• Prefer benchmark-compatible downstream paths: when compute_tvdi returns an environment-specific absolute path for the requested output artifact, normalize it back to benchmark/out/<question_folder>/tvdi_<discovered-date>.tif before thresholding when equivalence is clear.
• Use the exact returned path only when canonical benchmark normalization is not clearly justified.
• Preserve both representations when they differ: the returned artifact path and the normalized benchmark path.
• Pass threshold as a numeric value, not a quoted string.
• Do not add extra arguments such as mode unless the tool schema explicitly requires them.
• If pairing is missing or ambiguous, stop and report the blocker.
• Do not add extra tools in the normal case.
• Do not invent a percentage, drought-hotspot claim, or MCQ label when threshold computation is blocked.
• If a multiple-choice answer is required but threshold computation is blocked, explicitly state that no valid choice can be selected in the current runtime.

Failure handling

• If compute_tvdi fails from bad paths, rebuild full input paths from benchmark/data/<question_folder> and ensure output_path is benchmark-relative (<question_folder>/tvdi_<discovered-date>.tif), then retry once.
• If compute_tvdi returns no usable output path, fall back once to benchmark/out/<question_folder>/tvdi_<discovered-date>.tif only if that path is directly implied by the requested output artifact; otherwise stop and report an environment/path blocker.
• If calculate_threshold_ratio fails with an error containing GDAL, missing runtime, missing dependency, or equivalent environment wording, treat it as an environment blocker, not an analytical failure.
• After such a dependency error, do not claim completion, do not present partial success as task success, and do not guess the percentage or MCQ choice.
• Final blocked response must clearly say all of the following:
  • TVDI computation succeeded.
  • The threshold-exceedance step was blocked by the runtime/tool dependency.
  • The workflow logic and selected tools were appropriate.
  • No valid final percentage can be derived in the current runtime.
  • If MCQ formatted, no valid answer choice can be selected under the blocker.
• Final blocked response must include: failing tool name, exact error text, the path used for the failed threshold call, and the computed TVDI artifact location for retry (prefer the normalized benchmark path when available, but also surface the returned path when different).

See references/REFERENCE.md for canonical call patterns, path propagation examples, MCQ mapping, and blocked-execution response templates.