feat(tui): land welcome motion when the ocean is actually visible

[Hmbown]

Why

The 640ms idle whale / wordmark could finish while the launch menu still covered the ocean, so first visible idle looked still. Settings pickers also lacked a snappy presence settle.

What (Omarchy ethos, Codewhale material)

• Start the welcome clock only when launch/onboarding are not covering the mark
• Whale arrives with ease-out from ~87% presence (never from 0)
• One almost-linear shine pass
• Picker pop-in ~180ms, faster near-linear exit
• No workspace-slide, no bounce, no Hyprland chrome
• Reduced/Still skip decorative motion
• 70ms receipt stagger and 800ms fish flee unchanged

Does not replace PR #5643 (MCP login copy + ocean_started_at). welcome_visible_since is a separate clock.

Rebased onto current origin/main after #5648.

Tests

Focused TUI motion/underwater/picker tests + fmt + coauthor trailers.

No-Issue: welcome-motion polish; occlusion-aware surface clock, not a tracked GitHub issue.

Do not merge while required GitHub checks are red or still running.

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[claude]

Claude finished @Hmbown's task in 7m 10s —— View job

---

Review complete

• Gather context (diff, changed files, CLAUDE.md/AGENTS.md rules)
• Understand the request (code review only)
• Review correctness (motion/timing state machines, panics, exhaustiveness)
• Review provider/model/route safety implications (N/A — pure TUI motion PR)
• Review reuse/simplification/dead code
• Review test coverage
• Review security implications
• Post final review

Note: I was unable to run cargo test/cargo fmt in this sandbox (approval required for cargo invocations was not granted), so this review is source-only. The occlusion/timing logic reads correctly by inspection.

Summary

The welcome_visible_since occlusion clock, ease-out-quint arrival curve, and one-shot shine pass in crates/tui/src/tui/underwater.rs/motion/ethos.rs are well-scoped and cleanly separated from PR #5643's ocean_started_at clock, exactly as MOTION_ETHOS_HANDOFF.md describes. Tests for that lane (startup_surface_tests::*, the two widgets::tests::idle_welcome_* cases) look correct and actually exercise the occlusion/hand-off behavior.

Findings

1. The "picker pop-in" feature described in the PR/CHANGELOG is not actually wired to any renderer.

SettingsPickerController::settle_pop/is_settling (crates/tui/src/tui/settings_picker/controller.rs:312-326) are the only production call site of ethos::surface_pop/ethos::surface_exit. Neither method is ever called outside their own unit test:

$ grep -rn "settle_pop\|is_settling" --include="*.rs" . 
./crates/tui/src/tui/settings_picker/controller.rs  (definitions)
./crates/tui/src/tui/settings_picker/mod.rs         (unit test only)

theme_picker.rs::render (the only consumer of SettingsPickerController) never reads settle_pop/is_settling, and it isn't in this PR's changed-files list. So today a settings/theme picker renders at full opacity from frame one — the "~87% → 1.0 in 180ms" pop never actually paints.

MOTION_ETHOS_HANDOFF.md's own "Remaining" section is honest about this ("Live picker DIM needs a one-shot redraw while is_settling... This lane does not add a ViewAction::Redraw driver"), but the CHANGELOG.md entry states it as shipped fact: "Picker/menu pop uses the same 180 ms snappy settle" — with no such caveat, and docs/MOTION_CONTRACT.md's new Ethos section likewise doesn't flag it as unwired.

docs/MOTION_CONTRACT.md already has a precedent for exactly this situation ("Honesty note: catch-up is staged, not wired" — timing helpers exist and are tested, but no production call site drives them). This PR should either add the render-side wiring (even a no-redraw-driver version that just calls settle_pop once on first paint) or add the same kind of explicit "staged, not wired" note to docs/MOTION_CONTRACT.md and soften the CHANGELOG line so it doesn't read as shipped behavior.

Fix this →

2. Minor: welcome_surface_occluded duplicates part of idle_mark_animation_enabled.

ensure_welcome_surface_started (crates/tui/src/tui/underwater.rs:1537) checks both welcome_surface_occluded(app) (launch/onboarding) and !idle_mark_animation_enabled(app), but idle_mark_animation_enabled → decorative_shell_motion_enabled (underwater.rs:1513-1519) already requires !app.launch.visible && app.onboarding == OnboardingState::None. Not a bug (belt-and-suspenders, and the explicit check documents intent well), but the welcome_surface_occluded condition is currently redundant with logic already covered by idle_mark_animation_enabled. Low priority.

Good choices worth calling out

• Cleanly isolates its clock (welcome_visible_since) from PR fix(tui): recover MCP login and restore welcome motion #5643's in-flight ocean_started_at work, with an explicit non-collision rationale in both the field doc comment and handoff doc — reduces merge risk.
• ethos.rs centralizes the timing constants/curves with tests that assert relative properties (exit faster than entry, pop starts near 0.87, etc.) rather than pinning exact pixel/frame values — resilient test design.
• No panics/unwraps introduced; the new arithmetic (saturating_sub, guarded duration_ms == 0, bounded elapsed_ms >= WINDOW checks) is careful about edge cases.
• Reduced/Still correctly short-circuit to settled state in every new animated path (fade_opacity, surface_pop, surface_exit, ensure_welcome_surface_started).

[claude]

Claude finished @Hmbown's task in 1m 30s —— View job

---

Review complete

• Gather context (diff, changed files, CLAUDE.md/AGENTS.md rules)
• Understand the request (code review, PR synchronize trigger — new commit 12a7950)
• Review correctness (motion/timing state machines, panics, exhaustiveness)
• Review provider/model/route safety implications (N/A — pure TUI motion PR)
• Review reuse/simplification/dead code
• Review test coverage
• Review security implications
• Post final review

Summary

This synchronize adds one follow-up commit, 12a7950 ("keep welcome-motion helpers compiling under -Dwarnings"), on top of the previously-reviewed 26c217e. It's small: it sprinkles #[allow(dead_code)] over the ethos/picker-pop API, switches a runtime assert to a const { assert!(...) } compile-time check, extracts fish_flee_offset's magic 800 into ethos::FISH_FLEE_MS, and syncs crates/tui/CHANGELOG.md. These are mechanical and correct — the const-assertion works fine on this workspace's MSRV (rust-version = "1.88", inline const blocks stabilized in 1.79), and the FISH_FLEE_MS extraction is a good small dedup.

Findings

1. Still open: the "picker pop-in" is dead code with no production call site, and the CHANGELOG/docs still describe it as shipped.

The new commit's own message says it plainly: "Allow the unused chef's-choice ethos/picker DIM API until a redraw driver exists" — and every new #[allow(dead_code)] in crates/tui/src/tui/motion/ethos.rs and crates/tui/src/tui/settings_picker/controller.rs (settle_pop, is_settling, surface_pop, surface_exit, ease_out_exit, FADE_MS, SURFACE_EXIT_MS, fade_opacity) confirms it. I re-checked the current tree and settle_pop/is_settling are still called only from crates/tui/src/tui/settings_picker/mod.rs's unit test (crates/tui/src/tui/settings_picker/mod.rs:362-390) — theme_picker.rs, the only render-side consumer of SettingsPickerController, never calls either method.

Despite that, both CHANGELOG.md:12-19 and crates/tui/CHANGELOG.md:12-19 (unchanged by this commit) still state as fact: "Picker/menu pop uses the same 180 ms snappy settle" — with no caveat — and docs/MOTION_CONTRACT.md's new Ethos section (also unchanged) doesn't flag it as unwired either. This is exactly the situation docs/MOTION_CONTRACT.md already has a documented pattern for one section down ("Honesty note: catch-up is staged, not wired").

This commit had the chance to close that gap — it touches crates/tui/CHANGELOG.md and ethos.rs directly — but instead it codifies the unwired state with #[allow(dead_code)] comments rather than fixing the doc/changelog claim or adding the render-side call. Recommend either:

• adding a matching "picker pop-in is staged, not wired" honesty note under the Ethos section of docs/MOTION_CONTRACT.md and softening both CHANGELOG entries so "Picker/menu pop uses the same 180 ms snappy settle" doesn't read as shipped, or
• wiring settle_pop/is_settling into theme_picker.rs::render (even a no-redraw-driver version that blends opacity once on first paint).

Fix this →

2. Minor, unchanged from prior review: welcome_surface_occluded still duplicates part of idle_mark_animation_enabled (crates/tui/src/tui/underwater.rs:1537). Not a bug — belt-and-suspenders, and the redundant check documents intent. Low priority, no action needed.

Good choices worth calling out

• The new commit's fix is honest about the gap in its own commit message and code comments (// picker DIM host API; live redraw driver is a follow-up) even though the CHANGELOG/docs weren't updated to match — the code-level honesty just needs to propagate outward.
• fish_flee_offset's 800 → ethos::FISH_FLEE_MS extraction removes a duplicated magic number and keeps the one-shot timing centralized in ethos.rs, consistent with the module's stated purpose ("hosts should ask here rather than invent").
• const { assert!(SURFACE_EXIT_MS < SURFACE_POP_MS) } turns a previously-runtime invariant into a compile-time one — strictly stronger, and correctly scoped to this workspace's rust-version = "1.88".

Note: cargo test/cargo fmt were not run in this sandbox (no approval for cargo/network invocations); this review is source-only via git diff and grep.