Drop classifyEvent.ts, render TermMsg directly

Per review: StreamRow was meant to match what the server sends in
TermMsg, not be a separate model needing a translation step.

- classifyEvent.ts and streamRow.ts deleted; termMsg.ts holds the wire
  types (TermMsg/TermEnvelope) plus TermRow, a TermMsg with just the
  key/fromHistory bookkeeping Preact needs for list rendering.
- Row.tsx renders a TermRow directly: level -> CSS class, empty
  summary + markdown body -> flat row, everything else with a body ->
  expandable details gated by the operator's preference. No separate
  classification step.
- useLiveStream.ts drops ClassifyCtx (a single incrementing key
  counter didn't need a whole context object) and maps envelopes to
  rows inline.
- docs/terminal-rendering.md trimmed substantially — was documenting
  more implementation detail than useful; points at stream_enrich.rs
  for the per-tool specifics instead of duplicating them in prose.

frontend/packages/agent/src/components/Row.tsx

@@ -1,13 +1,16 @@
-// Renders one `StreamRow` — flat `<div class="row …">` or expandable
-// `<details class="row …">`, matching @hive/shared/terminal.css's
-// existing row-kind classes exactly (see docs/terminal-rendering.md).
-// Reuses that stylesheet as-is (imported once by LiveStream.tsx) — the
-// taxonomy's visual language isn't what mara asked to change, the
-// component *model* underneath it is.
+// Renders one `TermRow` — flat `<div class="row …">` or expandable
+// `<details class="row …">`, driven straight off the wire shape
+// (`lib/termMsg.ts`'s `TermMsg`, mirroring hive-agent's `term_msg.rs`):
+// `level` picks the colour class, an empty `summary` + markdown `body`
+// is a flat row with just the body (assistant text), anything else with
+// a body is an expandable details row gated by the operator's
+// expand-tool-output preference. No separate classification step —
+// mara: "StreamRow should now match what the server sends in TermMsg."
 import { useEffect, useRef } from 'preact/hooks';
-import type { StreamRow } from '../lib/streamRow.js';
+import type { TermRow } from '../lib/termMsg.js';
 import { linkifyToNodes } from '../lib/linkify.js';
 import { renderMarkdown } from '../lib/markdown.js';
+import { getExpandDetailsPref } from '@hive/shared/prefs.js';
 
 function MarkdownBody({ text }: { text: string }) {
   const ref = useRef<HTMLDivElement>(null);
@@ -41,25 +44,39 @@ function DiffBody({ text }: { text: string }) {
   );
 }
 
-export function Row({ row }: { row: StreamRow }) {
-  if (row.details) {
+export function Row({ row }: { row: TermRow }) {
+  const cssClass = 'level-' + row.level;
+  const icon = row.icon != null && row.icon !== '' && <span className="row-glyph">{row.icon}</span>;
+
+  if (row.body == null) {
     return (
-      <details className={`row ${row.cssClass}`} open={row.defaultOpen || undefined}>
-        <summary>
-          {row.icon != null && row.icon !== '' && <span className="row-glyph">{row.icon}</span>}
-          <span className="summary-text">{row.text}</span>
-        </summary>
-        {row.diffBody != null && <DiffBody text={row.diffBody} />}
-        {row.markdownBody != null && <MarkdownBody text={row.markdownBody} />}
-        {row.plainBody != null && <pre className="tool-body">{linkifyToNodes(row.plainBody)}</pre>}
-      </details>
+      <div className={`row ${cssClass}`}>
+        {icon}
+        {linkifyToNodes(row.summary)}
+      </div>
     );
   }
+
+  // Empty summary + markdown body → the body itself is the whole row
+  // (assistant text), no summary prefix line, never collapsible.
+  if (row.body_format === 'markdown' && row.summary === '') {
+    return (
+      <div className={`row ${cssClass}`}>
+        {icon}
+        <MarkdownBody text={row.body} />
+      </div>
+    );
+  }
+
   return (
-    <div className={`row ${row.cssClass}`}>
-      {row.icon != null && row.icon !== '' && <span className="row-glyph">{row.icon}</span>}
-      {row.text != null && linkifyToNodes(row.text)}
-      {row.markdownBody != null && <MarkdownBody text={row.markdownBody} />}
-    </div>
+    <details className={`row ${cssClass}`} open={getExpandDetailsPref() || undefined}>
+      <summary>
+        {icon}
+        <span className="summary-text">{row.summary}</span>
+      </summary>
+      {row.body_format === 'diff' && <DiffBody text={row.body} />}
+      {row.body_format === 'markdown' && <MarkdownBody text={row.body} />}
+      {row.body_format == null && <pre className="tool-body">{linkifyToNodes(row.body)}</pre>}
+    </details>
   );
 }