What

Info-message alerts on the Main tab now have a close button. Dismissals follow the firing: hidden while the message is in the workflow output, surface fresh if the workflow stops emitting it and later re-emits.

Why

Workflow advisories (vhh(), peptidesShortInstability(), partialChainMissingFullChain(), etc.) render on every Main view with no way to acknowledge. For inputs that legitimately fire an advisory across many runs, users re-see the same banner on every navigation. This PR adds the close affordance and ties dismissal to the firing so a different input that re-fires the same string shows fresh instead of staying silently suppressed.

How

State lives in a module-scope ref<Set<string>> in app.ts:

• PlAlert close emit → dismissInfoMessage(m) adds to the set.
• visibleInfoMessages computed filters outputs.info?.messages by the set.
• watch(() => outputs.info?.messages, ...) prunes the set to the intersection with the current output on every re-emit.

Hairpin-safe: writes are user gestures and output → local-ref, both sanctioned by harnesses/block-dev/hairpin.md. No BlockData change, no migration.

Lifetime

Dismissals live as long as the block UI's JS context.

• Survive: in-block navigation, switching to ≤3 other blocks and back (desktop LRU cache, limit 4), workflow re-runs where the message keeps firing.
• Reset: switching to ≥4 other blocks and back (LRU eviction), project close, block reload, app restart.
• Prune (not reset): workflow re-runs where a previously-dismissed message stops firing — entry drops from the set, a later re-fire surfaces fresh.

PR #12 prototyped a server-persisted alternative — closed because it gave "dismissed once, dismissed forever" semantics across all future workflow runs that re-emitted the string.

Test plan

• pnpm build:dev clean
• Dismiss alert → switch within-block tabs → return → still hidden
• Dismiss alert → switch input so advisory stops firing → switch back → advisory shows fresh (auto-prune)
• Close and reopen project → advisory shows fresh

sequenceDiagram
    participant WF as Workflow Output
    participant Watch as watch (app.ts)
    participant DIM as dismissedInfoMessages (ref<Set>)
    participant Comp as visibleInfoMessages (computed)
    participant UI as PlAlert (MainPage.vue)
    participant User as User

    WF->>Watch: outputs.info.messages changes
    Watch->>DIM: prune to intersection with fired set
    DIM-->>Comp: reactive update
    WF-->>Comp: reactive update
    Comp->>UI: render only non-dismissed messages

    User->>UI: clicks close button
    UI->>Comp: "@update:model-value emitted"
    Comp->>DIM: dismissInfoMessage(message) → new Set + message
    DIM-->>Comp: reactive update
    Comp->>UI: message removed from visibleInfoMessages

    Note over Watch,DIM: On next output change where message is absent,<br/>entry is pruned → future re-fire shows fresh

_{Reviews (3): Last reviewed commit: "docs: tighten changeset body" | Re-trigger Greptile}