feat(web): redesign Knowledge as an editable wiki

Replaces the read-only stats dashboard with a three-pane wiki: a
navigator tree (group by folder/type/tag/entity), a reader/editor with
bare-slug auto-linking and revision history + diff, and a context rail
for backlinks and related notes. Adds a Cleanup mode for the drift
tools (duplicates, tag manager, orphans, trash) and a Cmd+K quick-open.

Also:
- Adds a real landing view (hero count, KPI row, Nomos-share meter,
  recently-updated, busiest tags) in place of the old "Select a note"
  empty state, and extends the design pass across the tree/reader/rail
  (kind icons instead of repeated text badges, accent-bar selection,
  constrained prose measure).
- Guards every note-selection path behind a confirm when there's an
  unsaved edit in progress, so switching notes can no longer silently
  discard a draft.
- Extracts the markdown-rendering CSS duplicated across ChatThread,
  EntityDetailContent, and the new WikiReader into a shared
  .markdown-body class in app.css, with ChatThread keeping only its
  decorative deltas.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/lib/components/knowledge/WikiCleanup.svelte

@@ -0,0 +1,570 @@
+<script lang="ts">
+  // Maintenance view for the knowledge base's own drift — duplicates, tag
+  // casing splits, orphaned notes, and the trash. Surfaced as its own mode
+  // rather than folded into the main three-pane view because none of this
+  // is "browse a note," it's "audit the collection," and mixing the two
+  // would clutter the read/edit flow with tools most visits don't need.
+  //
+  // Every action here (merge, rename, restore) is deliberately one click
+  // away from a review step, never automatic — see fetchKnowledgeDuplicates'
+  // own doc comment on why title-similarity clustering can't be trusted as
+  // a verdict (the five "Lifecycle: <verb> a node" runbooks cluster despite
+  // being genuinely distinct documents).
+  import {
+    fetchKnowledgeDuplicates,
+    fetchKnowledgeTags,
+    fetchKnowledgeOrphans,
+    fetchKnowledgeTrash,
+    renameKnowledgeTag,
+    mergeKnowledge,
+    restoreKnowledge,
+    KnowledgeApiError,
+    type KnowledgeDuplicateCluster,
+    type KnowledgeTag,
+    type KnowledgeOrphan,
+    type KnowledgeTrashItem
+  } from '$lib/api'
+  import * as Tabs from '$lib/components/ui/tabs'
+  import { Button } from '$lib/components/ui/button'
+  import { Input } from '$lib/components/ui/input'
+  import { Badge } from '$lib/components/ui/badge'
+  import Spinner from '$lib/components/Spinner.svelte'
+  import { toast } from 'svelte-sonner'
+  import { kindMeta } from './kinds'
+  import { relativeTime } from '$lib/utils'
+  import CopyIcon from '@lucide/svelte/icons/copy'
+  import TagIcon from '@lucide/svelte/icons/tag'
+  import GhostIcon from '@lucide/svelte/icons/ghost'
+  import Trash2Icon from '@lucide/svelte/icons/trash-2'
+  import RotateCcwIcon from '@lucide/svelte/icons/rotate-ccw'
+  import CheckIcon from '@lucide/svelte/icons/check'
+
+  let {
+    onSelect,
+    onChanged
+  }: {
+    onSelect: (slug: string) => void
+    // Fired after any mutation (merge, tag rename, restore) so the parent's
+    // note list — which this view reads a filtered copy of, indirectly —
+    // stays in sync.
+    onChanged: () => void
+  } = $props()
+
+  let tab = $state<'duplicates' | 'tags' | 'orphans' | 'trash'>('duplicates')
+
+  // Shared across every loader/action below: the read helpers in api.ts now
+  // throw KnowledgeApiError on a failed request instead of quietly returning
+  // an empty list, so a real outage can't be mistaken for "nothing to
+  // clean up" — see api.ts's comment on listKnowledge for the same fix
+  // applied to the main note list.
+  function errMsg(e: unknown): string {
+    return e instanceof KnowledgeApiError ? e.message : 'Request failed.'
+  }
+
+  // ─── Duplicates ───────────────────────────────────────────────────────
+  let clusters = $state<KnowledgeDuplicateCluster[] | null>(null)
+  let duplicatesError = $state('')
+  // Per cluster (indexed by the cluster's first member slug — stable across
+  // a reload since clusters are keyed by content, not array position):
+  // which slug is the merge target and which sources are checked.
+  let mergeTarget = $state<Record<string, string>>({})
+  let mergeSources = $state<Record<string, Set<string>>>({})
+  let merging = $state<string | null>(null)
+  let mergeError = $state('')
+
+  async function loadDuplicates(): Promise<void> {
+    clusters = null
+    duplicatesError = ''
+    try {
+      const result = await fetchKnowledgeDuplicates()
+      clusters = result
+      const targets: Record<string, string> = {}
+      const sources: Record<string, Set<string>> = {}
+      for (const c of result) {
+        const key = c.members[0].slug
+        targets[key] = c.members[0].slug // newest first — see the Go handler's sort
+        sources[key] = new Set(c.members.slice(1).map((m) => m.slug))
+      }
+      mergeTarget = targets
+      mergeSources = sources
+    } catch (e) {
+      duplicatesError = errMsg(e)
+      clusters = [] // stop the spinner — the error message above explains the empty state
+    }
+  }
+
+  // A merge target switch leaves the PREVIOUS target unchecked (it's not in
+  // `sources` since it used to be excluded as "the target"), so recompute
+  // the whole source set relative to the new target rather than leaving it
+  // stale — otherwise the old target silently drops out of the merge
+  // instead of folding in like every other member.
+  function setMergeTarget(clusterKey: string, newTarget: string, allSlugs: string[]): void {
+    mergeTarget = { ...mergeTarget, [clusterKey]: newTarget }
+    mergeSources = {
+      ...mergeSources,
+      [clusterKey]: new Set(allSlugs.filter((s) => s !== newTarget))
+    }
+  }
+
+  function toggleSource(clusterKey: string, slug: string): void {
+    const set = new Set(mergeSources[clusterKey])
+    if (set.has(slug)) set.delete(slug)
+    else set.add(slug)
+    mergeSources = { ...mergeSources, [clusterKey]: set }
+  }
+
+  async function doMerge(clusterKey: string): Promise<void> {
+    const target = mergeTarget[clusterKey]
+    const sources = [...(mergeSources[clusterKey] ?? [])]
+    if (!target || sources.length === 0) return
+    merging = clusterKey
+    mergeError = ''
+    try {
+      const result = await mergeKnowledge(target, sources)
+      toast.success(`Merged ${result.merged.length} note${result.merged.length === 1 ? '' : 's'}`)
+      onChanged()
+      await loadDuplicates()
+    } catch (e) {
+      mergeError = errMsg(e)
+    } finally {
+      merging = null
+    }
+  }
+
+  // ─── Tags ─────────────────────────────────────────────────────────────
+  let tags = $state<KnowledgeTag[] | null>(null)
+  let tagsError = $state('')
+  let renaming = $state<string | null>(null)
+  let renameDraft = $state('')
+  let renameBusy = $state(false)
+
+  async function loadTags(): Promise<void> {
+    tags = null
+    tagsError = ''
+    try {
+      tags = await fetchKnowledgeTags()
+    } catch (e) {
+      tagsError = errMsg(e)
+      tags = []
+    }
+  }
+
+  async function normalize(t: KnowledgeTag): Promise<void> {
+    renameBusy = true
+    try {
+      const n = await renameKnowledgeTag(t.variants, t.tag)
+      toast.success(`Normalized "${t.tag}" across ${n} note${n === 1 ? '' : 's'}`)
+      onChanged()
+      await loadTags()
+    } catch (e) {
+      toast.error(errMsg(e))
+    } finally {
+      renameBusy = false
+    }
+  }
+
+  function startRename(t: KnowledgeTag): void {
+    renaming = t.tag
+    renameDraft = t.tag
+  }
+
+  async function confirmRename(t: KnowledgeTag): Promise<void> {
+    const to = renameDraft.trim().toLowerCase()
+    if (!to || to === t.tag) {
+      renaming = null
+      return
+    }
+    renameBusy = true
+    try {
+      const n = await renameKnowledgeTag(t.variants, to)
+      toast.success(`Renamed "${t.tag}" to "${to}" across ${n} note${n === 1 ? '' : 's'}`)
+      onChanged()
+      await loadTags()
+      renaming = null
+    } catch (e) {
+      // Leave the rename input open on failure — the operator's typed value
+      // (and their reason for changing it) shouldn't vanish along with the
+      // error, forcing them to retype it to try again.
+      toast.error(errMsg(e))
+    } finally {
+      renameBusy = false
+    }
+  }
+
+  // ─── Orphans ──────────────────────────────────────────────────────────
+  let orphans = $state<KnowledgeOrphan[] | null>(null)
+  let orphanCounts = $state<Record<string, number>>({})
+  let orphansError = $state('')
+
+  async function loadOrphans(): Promise<void> {
+    orphans = null
+    orphansError = ''
+    try {
+      const result = await fetchKnowledgeOrphans()
+      orphans = result.items
+      orphanCounts = result.counts
+    } catch (e) {
+      orphansError = errMsg(e)
+      orphans = []
+    }
+  }
+
+  // ─── Trash ────────────────────────────────────────────────────────────
+  let trash = $state<KnowledgeTrashItem[] | null>(null)
+  let trashError = $state('')
+  let restoring = $state<string | null>(null)
+
+  async function loadTrash(): Promise<void> {
+    trash = null
+    trashError = ''
+    try {
+      trash = await fetchKnowledgeTrash()
+    } catch (e) {
+      trashError = errMsg(e)
+      trash = []
+    }
+  }
+
+  async function doRestore(slug: string): Promise<void> {
+    restoring = slug
+    try {
+      await restoreKnowledge(slug)
+      toast.success('Note restored')
+      onChanged()
+      await loadTrash()
+    } catch (e) {
+      toast.error(errMsg(e))
+    } finally {
+      restoring = null
+    }
+  }
+
+  function activate(t: typeof tab): void {
+    tab = t
+    if (t === 'duplicates' && clusters === null) loadDuplicates()
+    else if (t === 'tags' && tags === null) loadTags()
+    else if (t === 'orphans' && orphans === null) loadOrphans()
+    else if (t === 'trash' && trash === null) loadTrash()
+  }
+
+  // Initial tab's data.
+  loadDuplicates()
+</script>
+
+<div class="flex h-full flex-col gap-2">
+  <Tabs.Root bind:value={tab} class="flex min-h-0 flex-1 flex-col">
+    <Tabs.List class="h-8 w-fit">
+      <Tabs.Trigger value="duplicates" class="gap-1 text-xs" onclick={() => activate('duplicates')}>
+        <CopyIcon class="size-3.5" /> Duplicates
+      </Tabs.Trigger>
+      <Tabs.Trigger value="tags" class="gap-1 text-xs" onclick={() => activate('tags')}>
+        <TagIcon class="size-3.5" /> Tags
+      </Tabs.Trigger>
+      <Tabs.Trigger value="orphans" class="gap-1 text-xs" onclick={() => activate('orphans')}>
+        <GhostIcon class="size-3.5" /> Orphans
+      </Tabs.Trigger>
+      <Tabs.Trigger value="trash" class="gap-1 text-xs" onclick={() => activate('trash')}>
+        <Trash2Icon class="size-3.5" /> Trash
+      </Tabs.Trigger>
+    </Tabs.List>
+
+    <Tabs.Content value="duplicates" class="min-h-0 flex-1 overflow-y-auto pt-2">
+      <p class="mb-2 text-xs text-muted-foreground">
+        Notes with near-identical titles, grouped for review — not a verdict. Pick a target and the
+        sources to fold into it; sources are soft-deleted afterward and stay recoverable from Trash.
+      </p>
+      {#if mergeError}
+        <p
+          class="mb-2 rounded border border-destructive/30 bg-destructive/5 px-2 py-1 text-xs text-destructive"
+        >
+          {mergeError}
+        </p>
+      {/if}
+      {#if duplicatesError}
+        <p class="mb-2 flex items-center gap-2 text-xs text-destructive">
+          {duplicatesError}
+          <Button size="sm" variant="outline" class="h-6 text-xs" onclick={loadDuplicates}
+            >Retry</Button
+          >
+        </p>
+      {/if}
+      {#if clusters === null}
+        <div class="flex justify-center py-8"><Spinner /></div>
+      {:else if clusters.length === 0}
+        <p class="py-8 text-center text-xs text-muted-foreground">No likely duplicates found.</p>
+      {:else}
+        <div class="flex flex-col gap-3">
+          {#each clusters as c (c.members[0].slug)}
+            {@const key = c.members[0].slug}
+            {@const sourceCount = mergeSources[key]?.size ?? 0}
+            <div class="overflow-hidden rounded-lg border">
+              <div
+                class="flex items-center justify-between gap-2 border-b bg-muted/30 px-2.5 py-1.5"
+              >
+                <div class="flex min-w-0 items-center gap-2 text-xs">
+                  <span class="font-medium">{c.members.length} similar notes</span>
+                  <!-- Similarity as a meter rather than only a number: it's a
+                       ratio, and the bar makes a 93% pileup visibly different
+                       from a borderline 61% at a glance down a long list. -->
+                  <span
+                    class="hidden h-1 w-12 shrink-0 overflow-hidden rounded-full bg-primary/15 sm:block"
+                    title="{(c.top_similarity * 100).toFixed(0)}% title similarity"
+                  >
+                    <span
+                      class="block h-full rounded-full bg-primary"
+                      style="width: {c.top_similarity * 100}%"
+                    ></span>
+                  </span>
+                  <span class="shrink-0 tabular-nums text-muted-foreground"
+                    >{(c.top_similarity * 100).toFixed(0)}%</span
+                  >
+                </div>
+                <Button
+                  size="sm"
+                  class="h-6 shrink-0 gap-1 text-xs"
+                  disabled={merging === key || sourceCount === 0}
+                  onclick={() => doMerge(key)}
+                >
+                  {merging === key ? 'Merging…' : `Merge ${sourceCount} into target`}
+                </Button>
+              </div>
+              <!-- Two bare inputs per row read as "…what do these do?", so
+                   name them once per cluster. An inline legend rather than
+                   column headers: the controls are 14px wide and the words
+                   are not, so headers sized to the columns just collide. -->
+              <p class="flex items-center gap-3 px-2.5 pt-2 text-[10px] text-muted-foreground">
+                <span class="flex items-center gap-1">
+                  <span
+                    class="inline-block size-2 rounded-full ring-1 ring-muted-foreground/60"
+                    aria-hidden="true"
+                  ></span> keep as target
+                </span>
+                <span class="flex items-center gap-1">
+                  <span
+                    class="inline-block size-2 rounded-[2px] ring-1 ring-muted-foreground/60"
+                    aria-hidden="true"
+                  ></span> fold into it
+                </span>
+              </p>
+              <div class="flex flex-col p-1">
+                {#each c.members as m (m.slug)}
+                  {@const isTarget = mergeTarget[key] === m.slug}
+                  {@const Icon = kindMeta(m.kind).icon}
+                  <label
+                    class="flex items-center gap-2 rounded px-1.5 py-1 text-xs {isTarget
+                      ? 'bg-primary/5'
+                      : 'hover:bg-muted/40'}"
+                  >
+                    <input
+                      type="radio"
+                      class="size-3.5 shrink-0 accent-[var(--primary)]"
+                      name="target-{key}"
+                      aria-label="Keep &quot;{m.title}&quot; as the merge target"
+                      checked={isTarget}
+                      onchange={() =>
+                        setMergeTarget(
+                          key,
+                          m.slug,
+                          c.members.map((mm) => mm.slug)
+                        )}
+                    />
+                    <input
+                      type="checkbox"
+                      class="size-3.5 shrink-0 accent-[var(--primary)]"
+                      aria-label="Fold &quot;{m.title}&quot; into the target"
+                      disabled={isTarget}
+                      checked={!isTarget && (mergeSources[key]?.has(m.slug) ?? false)}
+                      onchange={() => toggleSource(key, m.slug)}
+                    />
+                    <Icon class="size-3 shrink-0 text-muted-foreground/70" />
+                    <button
+                      type="button"
+                      class="min-w-0 flex-1 truncate text-left hover:underline {isTarget
+                        ? 'font-medium text-primary'
+                        : ''}"
+                      onclick={() => onSelect(m.slug)}
+                    >
+                      {m.title}
+                    </button>
+                    <span class="shrink-0 text-[10px] text-muted-foreground"
+                      >{relativeTime(m.updated_at)}</span
+                    >
+                    {#if isTarget}
+                      <Badge
+                        variant="outline"
+                        class="shrink-0 border-primary/40 text-[9px] text-primary">target</Badge
+                      >
+                    {/if}
+                  </label>
+                {/each}
+              </div>
+            </div>
+          {/each}
+        </div>
+      {/if}
+    </Tabs.Content>
+
+    <Tabs.Content value="tags" class="min-h-0 flex-1 overflow-y-auto pt-2">
+      {#if tagsError}
+        <p class="mb-2 flex items-center gap-2 text-xs text-destructive">
+          {tagsError}
+          <Button size="sm" variant="outline" class="h-6 text-xs" onclick={loadTags}>Retry</Button>
+        </p>
+      {/if}
+      {#if tags === null}
+        <div class="flex justify-center py-8"><Spinner /></div>
+      {:else}
+        {@const maxUses = Math.max(1, ...tags.map((t) => t.uses))}
+        <table class="w-full text-xs">
+          <thead>
+            <tr class="border-b text-left text-muted-foreground">
+              <th class="py-1 font-normal">Tag</th>
+              <th class="py-1 font-normal" colspan="2">Uses</th>
+              <th class="py-1 font-normal">Variants</th>
+              <th class="py-1"></th>
+            </tr>
+          </thead>
+          <tbody>
+            {#each tags as t (t.tag)}
+              <tr class="border-b border-border/50">
+                <td class="py-1 pr-2">
+                  {#if renaming === t.tag}
+                    <div class="flex items-center gap-1">
+                      <Input bind:value={renameDraft} class="h-6 w-32 text-xs" />
+                      <Button
+                        size="sm"
+                        class="h-6 px-1.5"
+                        disabled={renameBusy}
+                        onclick={() => confirmRename(t)}
+                      >
+                        <CheckIcon class="size-3" />
+                      </Button>
+                    </div>
+                  {:else}
+                    <button
+                      type="button"
+                      class="font-mono hover:underline"
+                      onclick={() => startRename(t)}
+                    >
+                      {t.tag}
+                    </button>
+                  {/if}
+                </td>
+                <!-- tabular-nums here (unlike the overview's standalone
+                     figures): these are a column that has to line up. -->
+                <td class="w-8 py-1 pr-1 text-right tabular-nums">{t.uses}</td>
+                <td class="w-24 py-1 pr-3">
+                  <!-- Magnitude, so: one hue, length-encoded, scaled to the
+                       most-used tag. Recessive by design — it's a reading aid
+                       down the column, not the subject of the table. -->
+                  <span class="block h-1 overflow-hidden rounded-full bg-primary/10">
+                    <span
+                      class="block h-full rounded-full bg-primary/60"
+                      style="width: {(t.uses / maxUses) * 100}%"
+                    ></span>
+                  </span>
+                </td>
+                <td class="py-1 pr-2">
+                  {#if t.split}
+                    <span class="text-destructive">{t.variants.join(', ')}</span>
+                  {:else}
+                    <span class="text-muted-foreground">—</span>
+                  {/if}
+                </td>
+                <td class="py-1 text-right">
+                  {#if t.split}
+                    <Button
+                      size="sm"
+                      variant="outline"
+                      class="h-6 text-xs"
+                      disabled={renameBusy}
+                      onclick={() => normalize(t)}
+                    >
+                      Normalize
+                    </Button>
+                  {/if}
+                </td>
+              </tr>
+            {/each}
+          </tbody>
+        </table>
+      {/if}
+    </Tabs.Content>
+
+    <Tabs.Content value="orphans" class="min-h-0 flex-1 overflow-y-auto pt-2">
+      <p class="mb-2 text-xs text-muted-foreground">
+        Notes untagged, unlinked to any entity, or untouched for 90+ days — invisible to most
+        navigation paths and easy to lose track of.
+        {#if orphanCounts.untagged || orphanCounts.unlinked || orphanCounts.stale}
+          ({orphanCounts.untagged ?? 0} untagged · {orphanCounts.unlinked ?? 0} unlinked · {orphanCounts.stale ??
+            0} stale)
+        {/if}
+      </p>
+      {#if orphansError}
+        <p class="mb-2 flex items-center gap-2 text-xs text-destructive">
+          {orphansError}
+          <Button size="sm" variant="outline" class="h-6 text-xs" onclick={loadOrphans}
+            >Retry</Button
+          >
+        </p>
+      {/if}
+      {#if orphans === null}
+        <div class="flex justify-center py-8"><Spinner /></div>
+      {:else if orphans.length === 0}
+        <p class="py-8 text-center text-xs text-muted-foreground">Nothing orphaned.</p>
+      {:else}
+        <div class="flex flex-col gap-0.5">
+          {#each orphans as o (o.slug)}
+            <button
+              type="button"
+              class="flex items-center gap-2 rounded px-1.5 py-1 text-left text-xs hover:bg-muted/40"
+              onclick={() => onSelect(o.slug)}
+            >
+              <span class="min-w-0 flex-1 truncate">{o.title}</span>
+              {#each o.reasons as r (r)}<Badge variant="outline" class="shrink-0 text-[9px]"
+                  >{r}</Badge
+                >{/each}
+              <span class="shrink-0 text-[10px] text-muted-foreground"
+                >{relativeTime(o.updated_at)}</span
+              >
+            </button>
+          {/each}
+        </div>
+      {/if}
+    </Tabs.Content>
+
+    <Tabs.Content value="trash" class="min-h-0 flex-1 overflow-y-auto pt-2">
+      {#if trashError}
+        <p class="mb-2 flex items-center gap-2 text-xs text-destructive">
+          {trashError}
+          <Button size="sm" variant="outline" class="h-6 text-xs" onclick={loadTrash}>Retry</Button>
+        </p>
+      {/if}
+      {#if trash === null}
+        <div class="flex justify-center py-8"><Spinner /></div>
+      {:else if trash.length === 0}
+        <p class="py-8 text-center text-xs text-muted-foreground">Trash is empty.</p>
+      {:else}
+        <div class="flex flex-col gap-0.5">
+          {#each trash as t (t.slug)}
+            <div class="flex items-center gap-2 rounded px-1.5 py-1 text-xs hover:bg-muted/40">
+              <span class="min-w-0 flex-1 truncate">{t.title}</span>
+              <span class="shrink-0 text-[10px] text-muted-foreground">
+                deleted {relativeTime(t.deleted_at)} by {t.deleted_by || 'unknown'}
+              </span>
+              <Button
+                size="sm"
+                variant="outline"
+                class="h-6 shrink-0 gap-1 text-xs"
+                disabled={restoring === t.slug}
+                onclick={() => doRestore(t.slug)}
+              >
+                <RotateCcwIcon class="size-3" /> Restore
+              </Button>
+            </div>
+          {/each}
+        </div>
+      {/if}
+    </Tabs.Content>
+  </Tabs.Root>
+</div>