chore: sync .cursor from suite

.cursor/skills/research/steps/03_engine-investigation.md

@@ -192,7 +192,7 @@ For every component/tool/library/service/pattern/algorithm that may be selected
 
 **API Capability Verification — Per-Mode (MANDATORY, BLOCKING for lead candidates)**:
 
-**Applicability**: this section applies only when the run is classified as **Technical-component selection** in the SKILL's Research Output Class section, and only to lead candidates that are libraries/SDKs/frameworks/services/protocols/data formats with multiple modes or configurations. For non-technical research (concept comparison, market/policy investigation, knowledge organization, root-cause analysis without tooling commitments), skip this entire sub-section and continue with the rest of Step 2 — the broader candidate implementation-limit search above is sufficient. State the skip explicitly once in `02_fact_cards.md`: `API Capability Verification: not applicable — this run is a Non-technical investigation, no library/SDK/service candidates`.
+**Applicability**: this section applies only when the run is classified as **Technical-component selection** in the SKILL's Research Output Class section, and only to lead candidates that are libraries/SDKs/frameworks/services/protocols/data formats with multiple modes or configurations. For non-technical research (concept comparison, market/policy investigation, knowledge organization, root-cause analysis without tooling commitments), skip this entire sub-section and continue with the rest of Step 2 — the broader candidate implementation-limit search above is sufficient. State the skip explicitly once in `02_fact_cards.md` (or in `02_fact_cards/00_summary.md` if split): `API Capability Verification: not applicable — this run is a Non-technical investigation, no library/SDK/service candidates`.
 
 Most libraries/SDKs/services expose **multiple modes or configurations** (e.g., monocular vs stereo VO, sync vs async API, batch vs streaming inference, write-through vs write-behind cache). Selecting a candidate "because it supports X" without pinning *which mode* the project will use, and *whether that exact mode produces the required outputs from the required inputs*, is the most common silent-failure path in research. A library can support a class of problem in mode A while being unusable for the project's specific configuration in mode B.
 
@@ -206,10 +206,10 @@ For every lead candidate that is a library/SDK/framework/service with multiple m
    2. *Project's exact mode*: "Show a minimum runnable example of `<library>` in `<the pinned mode>` with `<the project's input shape>`. What does it produce?"
    3. *Disqualifier probe*: "Does `<library>` `<the pinned mode>` produce `<the required output>`? Are there published limitations of `<the pinned mode>` for `<the project's runtime/hardware>`?"
 
-   For services without context7 coverage, use official docs site + WebFetch on the API reference page + the project's example/tutorial directory in the source repo. Append every consulted URL to `01_source_registry.md`.
+   For services without context7 coverage, use official docs site + WebFetch on the API reference page + the project's example/tutorial directory in the source repo. Append every consulted URL to `01_source_registry.md` (or the appropriate category file under `01_source_registry/` if split — see splittable-artifacts convention in `00_project-integration.md`).
 
 3. **Save a Minimum Viable Example (MVE) for the pinned mode.**
-   Append to `02_fact_cards.md` (or a sibling `02_mve_evidence.md`) at least one block per lead library candidate with:
+   Append to `02_fact_cards.md` / `02_fact_cards/` (or a sibling `02_mve_evidence.md`) at least one block per lead library candidate with:
 
    ```markdown
    ## MVE — <library> in <pinned mode>
@@ -225,7 +225,7 @@ For every lead candidate that is a library/SDK/framework/service with multiple m
    If no official example covers the project's exact configuration → the candidate cannot be marked `Selected` based on category fit alone. Status must be `Experimental only` (with required-evidence note) or `Rejected` (when the docs explicitly disqualify the configuration).
 
 4. **Bind every numbered Restriction and Acceptance Criterion to the candidate's pinned mode.**
-   For each numbered line in `restrictions.md` and `acceptance_criteria.md`, decide one of: `Pass` (the pinned mode satisfies it with cited evidence), `Fail` (the pinned mode contradicts it with cited evidence), `Verify` (no evidence either way; deeper investigation required), `N/A` (the line is irrelevant to this component area). Record this in `02_fact_cards.md` under the candidate's MVE block. The structural matrix in Step 7.5 reads from these bindings.
+   For each numbered line in `restrictions.md` and `acceptance_criteria.md`, decide one of: `Pass` (the pinned mode satisfies it with cited evidence), `Fail` (the pinned mode contradicts it with cited evidence), `Verify` (no evidence either way; deeper investigation required), `N/A` (the line is irrelevant to this component area). Record this in `02_fact_cards.md` (or the candidate's per-component file under `02_fact_cards/` if split) under the candidate's MVE block. The structural matrix in Step 7.5 reads from these bindings.
 
 5. **Treat "the same library in a different mode" as a different candidate.**
    If the project's pinned mode is `Monocular` but the only documented evidence covers `Stereo`, do not silently soften "rotation only" into "rotation + translation". Open a separate candidate row for the Monocular mode, with its own MVE, fit assessment, and disqualifiers. Two modes of one library are two distinct candidates for the purposes of this gate.
@@ -243,7 +243,7 @@ For every lead candidate that is a library/SDK/framework/service with multiple m
 **Search saturation rule**: Continue searching until new queries stop producing substantially new information. If the last 3 searches only repeat previously found facts, the sub-question is saturated.
 
 **Save action**:
-For each source consulted, **immediately** append to `01_source_registry.md` using the entry template from `references/source-tiering.md`.
+For each source consulted, **immediately** append to `01_source_registry.md` (or the appropriate category file under `01_source_registry/` if split) using the entry template from `references/source-tiering.md`.
 
 ---
 
@@ -273,7 +273,7 @@ Transform sources into **verifiable fact cards**:
   - ❓ Low: Inference or from unofficial sources
 
 **Save action**:
-For each extracted fact, **immediately** append to `02_fact_cards.md`:
+For each extracted fact, **immediately** append to `02_fact_cards.md` (or the appropriate category file under `02_fact_cards/` if split):
 ```markdown
 ## Fact #[number]
 - **Statement**: [specific fact description]
@@ -318,7 +318,7 @@ After initial fact extraction, review what you have found and identify **knowled
    - Failure cases and edge conditions
    - Recent developments that may change the picture
 
-4. **Update artifacts**: Append new sources to `01_source_registry.md`, new facts to `02_fact_cards.md`
+4. **Update artifacts**: Append new sources to `01_source_registry.md`, new facts to `02_fact_cards.md` (use the appropriate category files under `01_source_registry/` and `02_fact_cards/` if split)
 
 **Exit criteria**: Proceed to Step 4 when:
 - Every sub-question has at least 3 facts with at least one from L1/L2