feat: document & audio corpus picker for all tools

- Add "Select from My Docs" button to all text tool forms; free-tier
  users see an upgrade modal, paid (CaveauAI) users get a searchable
  multi-select modal backed by /api/dashboard/documents.php
- Add "Select from My Audio" picker on Transcribe with single-select
  and a "Save to My Audio" button for persisting uploaded clips
- New PHP helpers in bootstrap.php: dbnToolsFetchDocChunks,
  dbnToolsClientIdFromSession, dbnToolsInjectDocContent
- timeline, ask, redact APIs prepend selected document content
  (fetched from client_chunks SQL) before the textarea text
- api/dashboard/audio-upload.php stores audio files on server and
  creates a client_documents row with source_type='audio'
- api/transcribe.php falls back to stored audio via audio_doc_id POST
  field when no file is uploaded
- api/dashboard/documents.php supports ?source_type= filter
- tools.js: doc_ids added to JSON payload; stored-audio transcribe path
- New assets/css/doc-picker.css, assets/js/doc-picker.js
- SQL migration: scripts/sql/audio_docs_column.sql

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

includes/bootstrap.php

@@ -1110,3 +1110,69 @@ function dbnToolsExtractCheckLegalBasis(string $text): string
     }
     return '';
 }
+
+// ── Document picker helpers ───────────────────────────────────────────────────
+
+/** Fetch text content of selected client documents as labelled blocks. */
+function dbnToolsFetchDocChunks(array $docIds, int $clientId): string
+{
+    if (empty($docIds) || $clientId <= 0) {
+        return '';
+    }
+    $db = dbnToolsDb();
+    $placeholders = implode(',', array_fill(0, count($docIds), '?'));
+    $stmt = $db->prepare(
+        "SELECT c.content, d.title AS doc_title, c.document_id
+         FROM client_chunks c
+         JOIN client_documents d ON d.id = c.document_id
+         WHERE c.client_id = ? AND c.document_id IN ($placeholders)
+           AND d.source_type != 'audio'
+         ORDER BY c.document_id, c.id ASC
+         LIMIT 500"
+    );
+    $stmt->execute(array_merge([$clientId], $docIds));
+    $byDoc = [];
+    foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {
+        $id = (int)$row['document_id'];
+        $byDoc[$id] ??= ['title' => (string)$row['doc_title'], 'chunks' => []];
+        $byDoc[$id]['chunks'][] = (string)$row['content'];
+    }
+    $parts = [];
+    foreach ($byDoc as $doc) {
+        $parts[] = '=== ' . $doc['title'] . " ===\n" . implode("\n\n", $doc['chunks']);
+    }
+    return implode("\n\n---\n\n", $parts);
+}
+
+/** Resolve client_id for the current CaveauAI session; returns 0 for SSO/free-tier users. */
+function dbnToolsClientIdFromSession(): int
+{
+    try {
+        $tenant = dbnToolsEnsureDashboardTenant();
+        return (int)($tenant['client_id'] ?? 0);
+    } catch (Throwable) {
+        return 0;
+    }
+}
+
+/**
+ * Inject selected corpus document content into $text if doc_ids are in the request input.
+ * No-ops silently for free-tier (SSO) users who have no client_documents.
+ */
+function dbnToolsInjectDocContent(array $input, string $text): string
+{
+    $raw = $input['doc_ids'] ?? [];
+    $ids = array_values(array_filter(array_map('intval', is_array($raw) ? $raw : explode(',', (string)$raw))));
+    if (empty($ids)) {
+        return $text;
+    }
+    $clientId = dbnToolsClientIdFromSession();
+    if ($clientId <= 0) {
+        return $text;
+    }
+    $docText = dbnToolsFetchDocChunks($ids, $clientId);
+    if ($docText === '') {
+        return $text;
+    }
+    return $docText . ($text !== '' ? "\n\n---\n\n" . $text : '');
+}

includes/layout_footer.php

@@ -22,11 +22,44 @@
     </section><!-- /workspace -->
 </main><!-- /appShell -->
 <?php require_once __DIR__ . '/footer.php'; ?>
+<link rel="stylesheet" href="/assets/css/doc-picker.css">
 <script src="assets/js/tools.js" defer></script>
 <?php if (!empty($extraScripts) && is_array($extraScripts)): foreach ($extraScripts as $extraScript): ?>
 <script src="<?= htmlspecialchars((string)$extraScript) ?>" defer></script>
 <?php endforeach; endif; ?>
 <script src="assets/js/corpus-save.js" defer></script>
+<script src="/assets/js/doc-picker.js" defer></script>
+
+<!-- Doc picker modal (shared across all tool pages) -->
+<div id="docPickerBackdrop" class="doc-picker-backdrop" hidden role="dialog" aria-modal="true" aria-labelledby="docPickerTitle">
+    <div class="doc-picker-dialog">
+        <div class="doc-picker-dialog__head">
+            <h3 id="docPickerTitle">Select from My Docs</h3>
+            <button class="doc-picker-dialog__close" aria-label="Close">&times;</button>
+        </div>
+        <input type="search" class="doc-picker-dialog__search" placeholder="Search documents…" aria-label="Search documents">
+        <div class="doc-picker-list" role="listbox" aria-multiselectable="true">
+            <p class="doc-picker-list__loading">Loading…</p>
+        </div>
+        <div class="doc-picker-dialog__foot">
+            <span class="doc-picker-dialog__count"></span>
+            <button class="doc-picker-dialog__confirm" disabled>Add to tool</button>
+        </div>
+    </div>
+</div>
+
+<!-- Upgrade modal for free-tier users -->
+<div id="docPickerUpgradeBackdrop" class="doc-picker-upgrade-backdrop" hidden role="dialog" aria-modal="true" aria-labelledby="docPickerUpgradeTitle">
+    <div class="doc-picker-upgrade-card">
+        <span class="doc-picker-upgrade-card__icon">📂</span>
+        <h3 id="docPickerUpgradeTitle">Plus &amp; Pro feature</h3>
+        <p>Select documents from your uploaded corpus and feed them directly into any tool. Available on Plus and Pro plans.</p>
+        <div class="doc-picker-upgrade-card__actions">
+            <a href="/pricing.php" class="doc-picker-upgrade-card__cta">View plans</a>
+            <button class="doc-picker-upgrade-card__dismiss">Maybe later</button>
+        </div>
+    </div>
+</div>
 
 <!-- Save-to-corpus dialog (shared across all tool pages) -->
 <dialog id="save-corpus-dialog" class="save-corpus-dialog">

includes/tool_form.php

@@ -72,6 +72,15 @@
                         <p class="alias-hint">Replace a name with a bracketed alias, e.g. &ldquo;David Jr&rdquo; &rarr; [Junior]</p>
                     </div>
 
+                    <div id="docPickerSection" class="doc-picker-section">
+                        <button type="button" id="docPickerBtn" class="doc-picker-btn" aria-haspopup="dialog">
+                            <svg class="doc-picker-btn__icon" width="16" height="16" viewBox="0 0 16 16" fill="none" aria-hidden="true"><path d="M3 2h7l3 3v9H3V2z" stroke="currentColor" stroke-width="1.4" stroke-linejoin="round"/><path d="M10 2v3h3" stroke="currentColor" stroke-width="1.4" stroke-linejoin="round"/><path d="M5 7h6M5 9.5h4" stroke="currentColor" stroke-width="1.2" stroke-linecap="round"/></svg>
+                            <span>Select from My Docs</span>
+                        </button>
+                        <div id="docPickerChips" class="doc-picker-chips" aria-label="Selected documents"></div>
+                        <input type="hidden" id="docPickerIds" name="doc_ids" value="">
+                    </div>
+
                     <label class="input-label" for="toolInput" id="inputLabel">Question</label>
                     <textarea id="toolInput" name="toolInput" rows="10" required></textarea>