Stacks: live SQL preview, side-by-side layout, cascade stale detection

- Two-column layout: config left, SQL panel right (equal halves)
- SQL panel shows formatted SQL (sql-formatter, 4-space indent)
- Live preview: SQL updates 400ms after any field/source/mapping change
- Run button executes edited SQL directly via new exec-sql endpoint
- generate_stack_view gains p_dry_run mode for preview without executing
- CASCADE drop detects dependent stacks, marks them stale in DB and status bar
- net_balance moved to last column in generated view
- Backfill 458 missing dcard rows and 123 missing chase rows from TPS migration bug

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

api/routes/stacks.js

@@ -98,6 +98,14 @@ module.exports = (pool) => {
         } catch (err) { next(err); }
     });
 
+    // Preview the SQL that would be generated (dry run — does not create the view)
+    router.get('/:name/view-sql', async (req, res, next) => {
+        try {
+            const result = await pool.query(`SELECT generate_stack_view(${lit(req.params.name)}, true) AS result`);
+            res.json(result.rows[0].result);
+        } catch (err) { next(err); }
+    });
+
     // Generate / refresh the dfv view
     router.post('/:name/view', async (req, res, next) => {
         try {
@@ -110,6 +118,33 @@ module.exports = (pool) => {
         } catch (err) { next(err); }
     });
 
+    // Execute custom SQL for the view (user-edited SQL)
+    router.post('/:name/exec-sql', async (req, res, next) => {
+        try {
+            const { sql } = req.body;
+            if (!sql) return res.status(400).json({ success: false, error: 'sql is required' });
+            await pool.query(`DROP VIEW IF EXISTS dfv.${req.params.name} CASCADE`);
+            await pool.query(sql);
+            await pool.query(`UPDATE dataflow.stacks SET view_generated_at = NOW() WHERE name = ${lit(req.params.name)}`);
+            // Detect stacks whose views were dropped by CASCADE
+            const staleResult = await pool.query(`
+                SELECT array_agg(name) AS names FROM dataflow.stacks
+                WHERE name != ${lit(req.params.name)}
+                  AND view_generated_at IS NOT NULL
+                  AND NOT EXISTS (
+                      SELECT 1 FROM pg_views WHERE schemaname = 'dfv' AND viewname = name
+                  )
+            `);
+            const cascadeStale = staleResult.rows[0].names || [];
+            if (cascadeStale.length) {
+                await pool.query(`UPDATE dataflow.stacks SET view_generated_at = NULL WHERE name = ANY($1)`, [cascadeStale]);
+            }
+            res.json({ success: true, cascade_stale: cascadeStale });
+        } catch (err) {
+            res.json({ success: false, error: err.message });
+        }
+    });
+
     // Calibrate balance offset given a known good balance at a specific date
     router.post('/:name/calibrate', async (req, res, next) => {
         try {

database/queries/stacks.sql

@@ -46,6 +46,7 @@ ALTER TABLE dataflow.stack_sources ADD COLUMN IF NOT EXISTS date_field TEXT;
 -- Drop old signatures before recreating
 DROP FUNCTION IF EXISTS calibrate_balance(TEXT, DATE, NUMERIC);
 DROP FUNCTION IF EXISTS upsert_stack_source(TEXT, TEXT, JSONB, INTEGER, NUMERIC);
+DROP FUNCTION IF EXISTS generate_stack_view(TEXT);
 
 ------------------------------------------------------
 -- Function: list_stacks
@@ -239,7 +240,7 @@ $$ LANGUAGE plpgsql STABLE;
 -- Each source CTE applies amount_sign and computes a per-source running balance.
 -- Outer SELECT adds net_balance across all sources.
 ------------------------------------------------------
-CREATE OR REPLACE FUNCTION generate_stack_view(p_stack_name TEXT)
+CREATE OR REPLACE FUNCTION generate_stack_view(p_stack_name TEXT, p_dry_run BOOLEAN DEFAULT false)
 RETURNS JSON AS $$
 DECLARE
     v_stack      dataflow.stacks%ROWTYPE;
@@ -258,6 +259,7 @@ DECLARE
     v_canon_cols    TEXT;
     v_src_bal_cols  TEXT;
     v_total_offset  NUMERIC := 0;
+    v_cascade_stale TEXT[];
 BEGIN
     SELECT * INTO v_stack FROM dataflow.stacks WHERE name = p_stack_name;
     IF NOT FOUND THEN
@@ -327,9 +329,7 @@ BEGIN
         RETURN json_build_object('success', false, 'error', 'Stack has no sources');
     END IF;
 
-    CREATE SCHEMA IF NOT EXISTS dfv;
     v_view := 'dfv.' || quote_ident(p_stack_name);
-    EXECUTE format('DROP VIEW IF EXISTS %s CASCADE', v_view);
 
     v_canon_cols := (
         SELECT string_agg(quote_ident(f->>'name'), ', ')
@@ -337,23 +337,21 @@ BEGIN
     );
 
     IF v_has_bal THEN
-        -- net_balance = sum of all signed amounts + total of all source offsets
-        -- This ensures net_balance = sum of per-source carried-forward balances on every row
         v_sql := format(
             'CREATE VIEW %s AS '
             'WITH %s, _stacked AS (SELECT * FROM %s) '
             'SELECT _source, _id, %s, '
-            'SUM(%I) OVER (ORDER BY %I ASC, _id ASC) + %s AS net_balance, '
+            '%s, '
-            '%s '
+            'SUM(%I) OVER (ORDER BY %I ASC, _id ASC) + %s AS net_balance '
             'FROM _stacked ORDER BY %I DESC, _id DESC',
             v_view,
             array_to_string(v_ctes, ', '),
             array_to_string(v_cte_names, ' UNION ALL SELECT * FROM '),
             v_canon_cols,
+            v_src_bal_cols,
             v_stack.amount_field,
             v_stack.date_field,
             v_total_offset,
-            v_src_bal_cols,
             v_stack.date_field
         );
     ELSE
@@ -368,9 +366,31 @@ BEGIN
         );
     END IF;
 
+    IF NOT p_dry_run THEN
+        CREATE SCHEMA IF NOT EXISTS dfv;
+        EXECUTE format('DROP VIEW IF EXISTS %s CASCADE', v_view);
         EXECUTE v_sql;
 
-    RETURN json_build_object('success', true, 'view', v_view, 'sql', v_sql);
+        -- Detect stacks whose views were dropped by CASCADE and mark them stale
+        SELECT array_agg(s.name) INTO v_cascade_stale
+        FROM dataflow.stacks s
+        WHERE s.name != p_stack_name
+          AND s.view_generated_at IS NOT NULL
+          AND NOT EXISTS (
+              SELECT 1 FROM pg_views v
+              WHERE v.schemaname = 'dfv' AND v.viewname = s.name
+          );
+
+        UPDATE dataflow.stacks SET view_generated_at = NULL
+        WHERE name = ANY(v_cascade_stale);
+    END IF;
+
+    RETURN json_build_object(
+        'success', true,
+        'view', v_view,
+        'sql', v_sql,
+        'cascade_stale', COALESCE(to_json(v_cascade_stale), '[]'::json)
+    );
 END;
 $$ LANGUAGE plpgsql;
 
@@ -410,6 +430,6 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql STABLE;
 
-COMMENT ON FUNCTION generate_stack_view IS 'Generate a UNION ALL view in dfv schema combining multiple sources with optional running balance';
+COMMENT ON FUNCTION generate_stack_view(TEXT, BOOLEAN) IS 'Generate a UNION ALL view in dfv schema combining multiple sources with optional running balance; p_dry_run=true returns SQL without executing';
 COMMENT ON FUNCTION calibrate_balance IS 'Given a known good balance at a date, compute the offset to add to balance_offset';
 COMMENT ON FUNCTION get_stack_balance IS 'Return the current running balance (last row) from the generated dfv view';

ui/package.json

@@ -12,7 +12,8 @@
   "dependencies": {
     "react": "^19.2.4",
     "react-dom": "^19.2.4",
-    "react-router-dom": "^7.13.2"
+    "react-router-dom": "^7.13.2",
+    "sql-formatter": "^15.7.3"
   },
   "devDependencies": {
     "@eslint/js": "^9.39.4",

ui/src/api.js

@@ -121,7 +121,9 @@ export const api = {
   deleteStack: (name) => request('DELETE', `/stacks/${name}`),
   upsertStackSource: (name, source, body) => request('PUT', `/stacks/${name}/sources/${source}`, body),
   removeStackSource: (name, source) => request('DELETE', `/stacks/${name}/sources/${source}`),
+  previewStackSql: (name) => request('GET', `/stacks/${name}/view-sql`),
   generateStackView: (name) => request('POST', `/stacks/${name}/view`),
+  execStackSql: (name, sql) => request('POST', `/stacks/${name}/exec-sql`, { sql }),
   getStackBalance: (name) => request('GET', `/stacks/${name}/balance`),
   calibrateBalance: (name, source, body) => request('POST', `/stacks/${name}/calibrate`, { ...body, source_name: source || null }),
 

ui/src/pages/Stacks.jsx

@@ -1,5 +1,14 @@
-import { useState, useEffect } from 'react'
+import { useState, useEffect, useRef } from 'react'
 import { api } from '../api'
+import { format as formatSql } from 'sql-formatter'
+
+function prettySql(sql) {
+  try {
+    return formatSql(sql, { language: 'postgresql', tabWidth: 4, keywordCase: 'upper' })
+  } catch {
+    return sql
+  }
+}
 
 const FIELD_TYPES = ['text', 'numeric', 'date']
 
@@ -79,7 +88,7 @@ function CalibrateModal({ stack, sourceName, onClose, onApply }) {
 
 // ── Stack panel ────────────────────────────────────────────────────────────────
 
-function StackPanel({ stack, sources, onUpdated, onStale, onViewGenerated }) {
+function StackPanel({ stack, sources, onUpdated, onStale, onViewGenerated, onSqlGenerated }) {
   const members = stack.sources || []
 
   const [label, setLabel] = useState(stack.label || '')
@@ -126,6 +135,22 @@ function StackPanel({ stack, sources, onUpdated, onStale, onViewGenerated }) {
     })
   }, [members.map(m => m.source_name).join(',')])
 
+  // Live SQL preview — debounced whenever fields, sources, or mappings change
+  const previewTimer = useRef(null)
+  useEffect(() => {
+    clearTimeout(previewTimer.current)
+    previewTimer.current = setTimeout(() => {
+      api.previewStackSql(stack.name)
+        .then(r => { if (r.success) onSqlGenerated?.(r.sql) })
+        .catch(() => {})
+    }, 400)
+    return () => clearTimeout(previewTimer.current)
+  }, [
+    JSON.stringify(fields),
+    JSON.stringify(srcCfg),
+    members.map(m => m.source_name).join(','),
+  ])
+
   // Auto-detect canonical amount/date field from field types
   const amountCanonical = fields.find(f => f.type === 'numeric')?.name || stack.amount_field
   const dateCanonical   = fields.find(f => f.type === 'date')?.name   || stack.date_field
@@ -316,7 +341,12 @@ function StackPanel({ stack, sources, onUpdated, onStale, onViewGenerated }) {
     try {
       const r = await api.generateStackView(stack.name)
       setViewResult(r)
-      if (r.success) { fetchBalance(); onViewGenerated?.(stack.name) }
+      if (r.success) {
+        fetchBalance()
+        onViewGenerated?.(stack.name)
+        onSqlGenerated?.(r.sql || '')
+        ;(r.cascade_stale || []).forEach(n => onStale?.(n))
+      }
     } catch (e) { setError(e.message) }
   }
 
@@ -547,16 +577,11 @@ function StackPanel({ stack, sources, onUpdated, onStale, onViewGenerated }) {
           </div>
         )}
         {balanceError && <p className="text-xs text-gray-400 mb-3">{balanceError}</p>}
-        {viewResult && (
+        {viewResult && !viewResult.success && (
-          <div className="text-xs">
+          <p className="text-xs text-red-500">{viewResult.error}</p>
-            {viewResult.success
-              ? <p className="text-green-600 mb-2">View created: <span className="font-mono">{viewResult.view}</span></p>
-              : <p className="text-red-500">{viewResult.error}</p>
-            }
-            {viewResult.sql && (
-              <pre className="bg-gray-50 p-2 rounded overflow-auto text-gray-500 leading-relaxed">{viewResult.sql}</pre>
         )}
-          </div>
+        {viewResult && viewResult.success && (
+          <p className="text-xs text-green-600">View created: <span className="font-mono">{viewResult.view}</span></p>
         )}
       </div>
 
@@ -581,6 +606,9 @@ export default function Stacks({ sources, onStackStale, onStackViewGenerated })
   const [creating, setCreating] = useState(false)
   const [newName, setNewName] = useState('')
   const [error, setError] = useState('')
+  const [sqlDraft, setSqlDraft] = useState('')
+  const [sqlRunning, setSqlRunning] = useState(false)
+  const [sqlResult, setSqlResult] = useState(null)
 
   async function load() {
     const s = await api.getStacks()
@@ -591,6 +619,8 @@ export default function Stacks({ sources, onStackStale, onStackViewGenerated })
     const s = await api.getStack(name)
     setStackDetail(s)
     setSelected(name)
+    setSqlDraft('')
+    setSqlResult(null)
   }
 
   useEffect(() => { load() }, [])
@@ -610,10 +640,24 @@ export default function Stacks({ sources, onStackStale, onStackViewGenerated })
   async function deleteStack(name) {
     if (!confirm(`Delete stack "${name}"?`)) return
     await api.deleteStack(name)
-    if (selected === name) { setSelected(null); setStackDetail(null) }
+    if (selected === name) { setSelected(null); setStackDetail(null); setSqlDraft(''); setSqlResult(null) }
     load()
   }
 
+  async function runSql() {
+    if (!sqlDraft.trim() || !selected) return
+    setSqlRunning(true); setSqlResult(null)
+    try {
+      const r = await api.execStackSql(selected, sqlDraft)
+      setSqlResult(r)
+      if (r.success) {
+        onStackViewGenerated?.(selected)
+        ;(r.cascade_stale || []).forEach(n => onStackStale?.(n))
+      }
+    } catch (e) { setSqlResult({ success: false, error: e.message }) }
+    finally { setSqlRunning(false) }
+  }
+
   return (
     <div className="p-6">
       {/* Stack list — horizontal row of cards */}
@@ -643,9 +687,10 @@ export default function Stacks({ sources, onStackStale, onStackViewGenerated })
         )}
       </div>
 
-      {/* Full-width config panel */}
       {stackDetail ? (
-        <>
+        <div className="flex gap-6 items-start">
+          {/* Left: config panel */}
+          <div className="flex-1 min-w-0">
             <h2 className="text-base font-semibold text-gray-800 mb-4">
               {stackDetail.label || stackDetail.name}
               {stackDetail.label && <span className="text-sm text-gray-400 font-normal ml-2">{stackDetail.name}</span>}
@@ -657,8 +702,41 @@ export default function Stacks({ sources, onStackStale, onStackViewGenerated })
               onUpdated={() => { load(); loadDetail(stackDetail.name) }}
               onStale={onStackStale}
               onViewGenerated={onStackViewGenerated}
+              onSqlGenerated={sql => { setSqlDraft(prettySql(sql)); setSqlResult(null) }}
             />
-        </>
+          </div>
+
+          {/* Right: SQL panel */}
+          <div className="flex-1 min-w-0">
+            <div className="bg-white border border-gray-200 rounded p-4 sticky top-4">
+              <div className="flex items-center justify-between mb-3">
+                <h3 className="text-sm font-semibold text-gray-700">Generated SQL</h3>
+                <button
+                  onClick={runSql}
+                  disabled={!sqlDraft.trim() || sqlRunning}
+                  className="text-sm bg-blue-600 text-white px-3 py-1 rounded hover:bg-blue-700 disabled:opacity-40">
+                  {sqlRunning ? 'Running…' : 'Run'}
+                </button>
+              </div>
+              {sqlDraft ? (
+                <textarea
+                  className="w-full font-mono text-xs text-gray-700 bg-gray-50 border border-gray-200 rounded p-2 focus:outline-none focus:border-blue-400 resize-none leading-relaxed"
+                  style={{ minHeight: '60vh' }}
+                  value={sqlDraft}
+                  onChange={e => { setSqlDraft(e.target.value); setSqlResult(null) }}
+                  spellCheck={false}
+                />
+              ) : (
+                <p className="text-xs text-gray-400">Generate a view to see the SQL here.</p>
+              )}
+              {sqlResult && (
+                <p className={`text-xs mt-2 ${sqlResult.success ? 'text-green-600' : 'text-red-500'}`}>
+                  {sqlResult.success ? 'View updated successfully.' : sqlResult.error}
+                </p>
+              )}
+            </div>
+          </div>
+        </div>
       ) : (
         <p className="text-sm text-gray-400">Select a stack or create one.</p>
       )}