Add intrinsic prompt-pack intervention for raw generation (sprint 261)

docs/sprint261_execution_tracker_2026-02-26.md

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+# Sprint 261 Execution Tracker - 2026-02-26
+
+## Scope
+- `sprint261_plan.md`
+
+## Implemented
+
+New tool:
+- `tools/mcp/synthesize_raw_intrinsic_prompt_pack.py`
+  - Builds a compact intrinsic prompt pack from top-gap signals.
+  - Encodes required ops, executionContract fields, reason keywords, and anti-generic-task constraints.
+
+Pipeline integration in `tools/mcp/run_sprint_taskitem_pipeline.sh`:
+- Added:
+  - `WSTONE_NATIVE_RAW_INTRINSIC_PROMPT_PACK`
+  - `WSTONE_NATIVE_RAW_INTRINSIC_PROMPT_MAX_SIGNALS`
+- Added artifacts:
+  - `01f_raw_intrinsic_prompt_pack_requirements.json`
+  - `01f_raw_intrinsic_prompt_pack_report.json`
+- Added summary packet:
+  - `native_raw_intrinsic_prompt_pack`
+
+## Validation Artifacts
+
+OFF:
+- `logs/taskitem_runs/01a_fallback_intake_spec_20260226_163844/00_summary.json`
+
+ON:
+- `logs/taskitem_runs/01a_fallback_intake_spec_20260226_163855/00_summary.json`
+- prompt-pack artifacts:
+  - `logs/taskitem_runs/01a_fallback_intake_spec_20260226_163855/01f_raw_intrinsic_prompt_pack_report.json`
+
+Observed result on hard sample:
+- prompt pack injected with selected signals (`selected_signal_count=8`)
+- `selected_variant` remained `0`
+- `best_top_gap_score` remained `0`
+- `failing_profile_count` remained `1`
+
+## Explicit Completion Signal
+
+- Sprint 261: `DONE` (implemented + validated; intrinsic uplift still pending)