# EC Parts Builder lib-6.1 release notes Status: published from Git tag `ec-parts-lib-6.1`. EC Parts Builder `lib-6.1` supersedes `lib-6.0` at the existing standalone URL: The Shopify presentation remains: Force Curve Bench remains `fc-3.4`. This release changes the Parts Builder, its structured catalog and compatibility presentation, and supporting documentation. It does not change any raw force-curve CSV, retained-run membership, canonical measurement, perception-index equation, or sealed evidence identity. ## What changed - The build surface expands from 9 to **11 component rows**. - A top-level **2u stabilizer assembly** can load a recorded 2u housing, slider, and silencing ring together. Each child part remains independently editable, and an edit marks the loaded assembly as modified. - A separate **2u silencing-ring** row exposes the same ring-seat geometry calculation used for the 1u stack. - The starting-point catalog expands to **28 keyboard starters** and **4 manufacturer-parts shortcuts**. The shortcuts intentionally load no dome and are not presented as verified working configurations. - The library includes **10 recorded 2u assemblies**, Topre Realforce Variable domes, NovaTouch 1u and stabilized-key parts, and additional Realforce and Leopold starting points. - Four short-spacebar Realforce starters explicitly load no separate spacebar stabilizer because the selected 2u assembly performs that role. - Eligible measured domes show **Weight Index**, **Tactility Index**, and **Force-Wall** in that order. The visible Travel result uses the earlier of ring-adjusted slider travel and the selected dome's detected Force-Wall. - **Dome compression** is shown separately from Travel. Null Force-Wall values remain **Not detected** and never borrow another specimen or the final sample. ## Ring-seat handling Both 1u and 2u stacks use: ```text total ring seat = slider ring seat + housing ring seat fit delta = total ring seat - ring thickness ``` Zero is flush, a negative value is compression, and a positive value is top-out clearance with possible chatter. The DynaCaps 0.05 mm and 0.25 mm pre-compression configurations are recognized as intentional only when the matching DynaCaps slider, housing, and supported ring are selected. The 0.5 mm Silicone ring is the default for the DynaCaps manufacturer shortcut and 2u assembly, matching the manufacturer recommendation. ## Compatibility presentation The complete compatibility configuration contains **3,570 edges**. The consumer payload contains **241 decision-changing pair edges** after 97 generic matrix-expanded spring edges are replaced by three part-scoped findings: - Deskeys conical spring: **Does not work**; - KLC conical spring: **Does not work**; and - MetaPulse conical spring: **Not verified**. Each finding appears once on the spring that causes it. Other selected parts are not blamed through repeated “spring + part” messages, while the whole-build status still inherits the spring's state. Genuine pair-specific findings remain active. An otherwise-unverified pair with the same canonical, nonempty manufacturer may receive **Manufacturer matched**. This is an explicit library policy, not a claim that the pairing was physically tested. Known conflicts, recorded conditions, and explicit compatible evidence take precedence. ## Verification and acceptance The final `lib-6.1-review.1` prepublication build passed: - byte-identical regeneration; - the 85-check Parts Builder runtime battery; - the complete generator test suite, with 518 tests passed and 13 declared environment-dependent skips; and - owner review followed by explicit publication authorization. The accepted review artifact's SHA-256 was `1f9150b6c1910ccef480dd3b561571e93ec7ca2da59f3fd273b6fa851193b546`. That value is retained only to identify the accepted review input. The public release bytes and complete site tree are authoritative only through `SITE_RELEASE_MANIFEST.json` and `SHA256SUMS`. ## Continuity and rollback The controlled overlay replaces `dome-lab-parts.html` and its declared generator/documentation inputs. It preserves the fc-3.4 viewer, all 184 raw CSV paths, the canonical-evidence tree, and every other protected continuity endpoint byte for byte. The historical `ec-parts-lib-6.0` tag and [`RELEASE_NOTES_lib-6.0.md`](RELEASE_NOTES_lib-6.0.md) remain the rollback and citation authority for the preceding release. See the [current Parts Builder guide](EC_PARTS_LIBRARY.md), [completed prepublication acceptance record](EC_PARTS_LIBRARY_LIB61_REVIEW.md), [compatibility audit](COMPAT_AUDIT_r8.md), and [verification instructions](REPRODUCING.md).