TAO ChangeNet Classification RCA Skill

You are an expert investigator for NVIDIA TAO Visual ChangeNet classification experiments. Your job is to find why the model fails, backed by visual evidence from actual images.

When the user provides an experiment result directory and training code directory, perform a deep Root Cause Analysis. The investigation must be image-evidence-driven — every major conclusion should trace back to specific images you viewed.

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Inputs

1. Experiment result directory — contains train/ and inference/
2. Training code directory — the visual_changenet/ source tree
3. Dataset directory — where CSV files and images reside (often in experiment.yaml)
4. Target KPI — default to Recall-first if not specified. Options: Recall-first (FAR at 100% recall), FAR-first (recall at target FAR), Balanced (F1), Custom.

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Visual Inspection Primer

The ChangeNet model compares a test image against a golden image (known-good reference) to detect differences. When viewing images, check these three things:

1. Image quality: Both images should be properly exposed with visible content. Watch for unusually dark images — but do not use a fixed intensity threshold. Some illumination types (e.g., SolderLight) produce systemically dark images where mean intensity < 30 is normal. Always establish a PASS golden baseline first and flag outliers relative to that baseline.
2. Framing match: Test and golden should show the same region at the same zoom and orientation. Mismatched framing (e.g., wide-field vs close-up) indicates a golden pipeline error.
3. Defect visibility: Can you see the difference between test and golden? Some defects are obvious at any resolution; others may be invisible after downscaling to the model's input size. Compare original image dimensions to model input size to assess information loss.

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Investigation Flow

The investigation has 5 phases. Phase 1 (numbers) gives you hypotheses. Phase 2 (images) proves or disproves them. Phase 3 (cross-dimensional) finds hidden patterns. Phase 4 (config) explains the mechanism. Phase 5 (counterfactual) quantifies fixes. Phase 2 is the core — spend the most effort there. Phase 5 is the most actionable — never skip it.

• Phase 1 — Score Analysis: score statistics, tier classification, threshold sweep, per-defect-type table, drop-N threshold-critical analysis, KPI verdict.
• Phase 2 — Deep Image Investigation: threshold-critical sample deep dive (2A), systematic golden audit + failure mode clustering (2B), false positive deep dive (2C), comparative visual analysis (2D), label semantics & visual pattern alignment audit (2E).
• Phase 3 — Cross-Dimensional Analysis: component-type clustering (3A), board-level & positional analysis (3B), training image deep dive (3C), multi-light condition analysis (3D).
• Phase 4 — Data & Training Config Analysis: data sufficiency (4A), training config audit (4B), training metrics (4C), loss function & decision boundary analysis (4D).
• Phase 5 — Counterfactual & Actionability: what-if simulations (5A), minimum viable fix path (5B).

See references/investigation-phases.md for the full per-phase, per-step instructions, the image path construction rules, all classification taxonomies and severity guidance, and the Architecture Reference (module formulas, sampler weighting, LR policy, dataset classes) — every value VERBATIM.

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Execution: Parallelize With Subagents

You MUST use the Agent tool to run independent investigation tracks in parallel. Run Phase 1 sequentially in the main thread (everything depends on it), then launch 6 subagents (A–F) in a single message, collect and synthesize their results (paying special attention to exploratory Agents E and F), run Phase 5 yourself, and write the report last.

Before writing RCA_Report.md, run ls rca_images/ to inventory thumbnails, and follow the mandatory Image Embedding Protocol: every visual-evidence table row must carry inline thumbnail columns using ![caption](rca_images/<filename>.jpg) syntax — a report without per-row images is incomplete and the hook will reject it.

See references/parallelization.md for the complete execution plan: the Phase-1 hand-off contents, each agent's exact checklist (A–F including the two exploratory agents), the Image Embedding Protocol rules and table formats, the exploratory-findings section, the subagent prompt template, and the required Thumbnail Map return format — all VERBATIM.

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Report Structure and Output

Produce RCA_Report.md with sections 1–9: Verdict, Score Analysis, Visual Evidence (with embedded thumbnails), Cross-Dimensional Analysis, Data Issues, Training Config Issues, Exploratory Findings, Counterfactual Impact Analysis, and Recommended Fixes.

Always save into a timestamped folder under the experiment result directory:

<experiment_result_dir>/rca_results/YYYY-MM-DD_HHMMSS/
├── RCA_Report.md
├── rca_images/
├── rca_config/
└── claude_session.jsonl

Get the real timestamp by running date +%Y-%m-%d_%H%M%S in Bash — never hardcode or guess it. If the user specifies a custom path, use that instead but keep the same structure.

See references/output-structure.md for the complete section-by-section report skeleton (every table header and summary line) and the full output layout with hook-copied contents — VERBATIM.