components: follow-ups for components, change detection and defer blocks #366

Items still open from the audit issue #344. The fixed items landed in #361; this issue tracks what is left. Each item says why it was not part of that fix.

From #344 (components, change detection and defer blocks)

Partly done (the rest is open):

• CD: limits hit silently (Low): A failed getHostElement is no longer cached as null, so the host is read again on the next snapshot (test added). droppedClasses/droppedHosts in CdRecording, LimitNote and the agent text are not done.
• Defer: no runtime @let (Medium, to confirm): Confirmed that Angular's debug API exposes no @let slots, so the gap is now documented under Limits and gotchas in components.md. No runtime listing.

Open:

• Components: no source location for directives; guessed fallback (Low): Touches three layers (source scan, tree detail, panel) and needs a 'likely' label in the UI. Too big for this batch.
• Components: changed values not visible / Show in Signals (Low): New panel feature with UX decisions (flash, cross-page link).
• Components improvement: pick by keyboard: New interaction design. Not a small local change.
• Components improvement: Copy as JSON / Copy host path: New panel actions. Needs a product decision on the format.
• CD: wrong 'needs Angular 20' message (Low): Needs a new reason field, retry logic and a version fallback across overlay, server, agent tool and panel. Larger than a local fix.
• CD: start confirmed without an answer from the page (Low): Needs a wait-for-push handshake in devframe and the panel. Cross-layer.
• CD: panel shows less than the agent tool / track $index (Low): The extra panel lists and links are feature work. track $index is deliberate: duplicate-track-keys.test.ts covers two classes with the same name, so track c.name would bring back the duplicate-key warning.
• CD improvement: keep recording across a reload: Changes behaviour (sessionStorage per pageId) and needs a product decision.
• CD improvement: slow cycle budget limits.cdSlowMs: New config option. That is public API.
• Defer: missing hydratedAt (Low): Needs a new 'hydrated before inspection' state shown in the panel and agent text. A product/UX choice.
• Defer: silent 500-block cap (Low): Needs a truncated flag through the collector, report shape, server, agent text and panel pill. Cross-layer.
• Defer: panel hides data it has (Low): New expandable row detail and badges. Panel feature work.
• Defer: clock skew (Low, to confirm): Confirmed (server Date.now() compared with the page's since), but the fix changes the report shape across page, server and tool. Left for a focused change.
• Defer: mismatch 'component' is a node name (Low): scanHydration has no ng access. Resolving the owner and adding fields changes the report shape.
• Defer: partial block highlight (Low): Needs request-page-highlight to accept several ids, a protocol change.
• Defer improvements (badges, force-load action tool, transition timeline, mismatch links, defer blocks in component detail): New features or tools, some depending on phase 3 of 4: a shell you live in #342. Not small or local.

Tracked elsewhere

These items from the audit are not listed above because another issue already tracks them:

• Opening the template file and line: phase 1 of 4: safe by default and wired into your workflow #340 (open in editor), landed in feat(hub): open in editor, dock group, messages and badges, and mcp --print-config #378