Fade overflowing sidebar labels

[gaelcado]

Replace ellipses on overflowing sidebar labels with a 20 px right-edge fade: active and archived session titles, branch names, project/device metadata, project-filter labels, and device group headings. Fitting labels remain opaque except for the existing vertical scroll fade.

Ease the right-edge fade into view as overflow grows. Preserve search highlighting, adjacent controls, branch/PR spacing, and the sidebar and command palette's vertical fades. Label fades inherit the active scroll container's vertical bounds and asymmetric fade bands; paint scopes are restored before siblings render. This fixes the reviewed regression where long labels stayed bright at vertical scroll edges.

Merge main while retaining both faded disclosure labels and the shared sidebar separator introduced by #407.

The existing renderer override remains pinned to gaelcado/zui@53869c204efb866d19af292cab8b1773898eeedd. Its entire source tree is identical to upstream zeronsh/zui@1561532176f54262e360acbb8bc00c6fcf183975 from merged zeronsh/zui#12. Migrating away from the override also requires aligning gpui-base's GPUI dependency pin.

Validation at cd247d721113a71065c2e4ca1ba92877beb78a9e:

• All 1,059 UI tests pass locally, including a new paint-level regression for nested fades, overflow transitions, asymmetric bands, and sibling scope restoration.
• Linux/X11 production Shell fixture rebuilt and inspected with synthetic sessions. Fitting and overflowing bottom-row title prefixes match pixel-for-pixel; overflowing labels retain their horizontal fade.
• Changed Rust files pass rustfmt; diff whitespace checks pass.
• Fresh screenshots are attached to the approval review. All executed cross-platform CI checks passed before merge.

[wingleeio]

Security audit and review of f7f73bd77cce890fdb837cb364d01c427a8607bb: requesting changes for the nested-fade rendering regression described inline. No actionable security vulnerability found in the reviewed change, but this revision should not merge yet.

Security scope: inspected the UI diff, all changes in the pinned renderer versus the previous renderer, dependency provenance, and shader/host data flow. The full source tree of fork commit 53869c204efb866d19af292cab8b1773898eeedd exactly matches merged upstream commit 1561532176f54262e360acbb8bc00c6fcf183975 (tree e5f21c24b5c7a161cb80b6a2c58c1a8c8382b065). No added application network access, command execution, authentication changes, or new unsafe Rust was found. The immutable renderer pin is unchanged in the tested candidate.

Validation and conflict handling:

• Prepared a local merge with main at b4dd24d7346a50fe73658d06e4d75ddb9a61c50e. Resolved the disclosure-header conflict by keeping both this PR's faded label and main's shared sidebar_separator helper. Nothing was pushed.
• On that locally resolved candidate, cargo test --locked -p zeron-ui --lib -- --test-threads=1 passed 1,058 tests, 0 failures. Changed Rust files pass rustfmt and the diff passes whitespace checks.
• Built and ran an isolated Linux/X11 production Shell fixture with synthetic sessions. Two otherwise identical 1100×440 windows differ only in whether titles fit or overflow horizontally. The overflowing Session 04 remains fully bright at the bottom scroll edge; the fitting Session 04 correctly fades. The adjacent icon still fades in both cases, making the inconsistency visible.
• Existing PR CI and the pinned renderer's Windows CI succeeded. Those tests do not cover nested horizontal/vertical fades. The renderer's WGPU unit test cannot be invoked directly through the application's workspace because it is a dependency with its own dev-dependencies; no new local shader-test pass is claimed.

Fresh GitHub user attachments from the controlled fixture (look at the bottom Session 04 row):

Overflowing labels: vertical fade is lost

Fitting labels: vertical fade remains active

[wingleeio]

Fixed and re-audited cd247d721113a71065c2e4ca1ba92877beb78a9e. The original nested-fade finding is resolved; no remaining actionable security or correctness findings.

The conflict resolution preserves both the faded disclosure label and main's shared sidebar separator. The only additional implementation change retains the active wrapper fade during painting, keyed by window, and carries its vertical bounds and independent top/bottom bands into overflowing label fades. Fitting labels inherit the original parent scope; paint state is restored after each child. Interior mutability avoids scheduling global-observer notifications for each painted label. No dependency revision, network, command execution, authentication, or unsafe-memory changes were added by the fix. The pinned renderer source tree remains identical to the previously audited upstream merge.

Validation:

• Full local UI suite: 1,059 passed, 0 failed.
• New paint-level regression exercises fitting → overflowing → fitting behavior through repeated width changes, top-only/bottom-only/combined/no vertical fades, asymmetric bands, and restoration for siblings and elements outside the scroll container.
• Rebuilt and reran the Linux/X11 production Shell fixture that exposed the bug. The bottom-row Session 04 prefix now matches pixel-for-pixel between overflowing and fitting titles (x=86..152, y=469..484), while long text retains its right-edge fade.
• Changed-file rustfmt and diff whitespace checks passed. No intervening PR or main changes were found before applying this fix.

Fresh GitHub user attachments from the fixed build, using isolated synthetic sessions. Cross-platform CI is running on the pushed head at review submission; these screenshots are Linux fixture evidence.

Fixed overflowing title: horizontal and vertical fades both apply

Fitting title: matching vertical fade at the bottom edge