diff --git a/scripts/check-jsonb-params.mjs b/scripts/check-jsonb-params.mjs
new file mode 100644
index 000000000..f3be2ddab
--- /dev/null
+++ b/scripts/check-jsonb-params.mjs
@@ -0,0 +1,128 @@
+#!/usr/bin/env node
+/**
+ * CI guard for the POSITIONAL jsonb double-encode footgun (#2339 / #2324 class).
+ *
+ * The legacy scripts/check-jsonb-pattern.sh only catches the template-tag form
+ * (`${JSON.stringify(x)}::jsonb`). It MISSES the positional-param form:
+ *
+ *     engine.executeRaw(`... $3::jsonb ...`, [a, b, JSON.stringify(x)])
+ *
+ * Under postgres.js `.unsafe(sql, params)` a JS STRING bound to a `$N::jsonb`
+ * param double-encodes — the text→jsonb cast wraps the already-JSON string into a
+ * jsonb *string scalar*. PGLite parses it silently, so the bug is invisible in
+ * unit tests and only bites on real Postgres (it aborted every sync in #2339).
+ *
+ * This scanner flags any executeRaw / executeRawDirect / .unsafe(...) call whose
+ * balanced argument span contains BOTH a positional `$N::jsonb` cast
+ * (NOT `$N::text::jsonb`, NOT `$N::text[]`) AND a `JSON.stringify(` — the exact
+ * double-encode shape. It is heuristic by design (whole-span correlation); the
+ * real backstop is the DATABASE_URL-gated e2e parity test. Keep both.
+ *
+ * Allowed forms (NOT flagged):
+ *   - `$N::text::jsonb` + JSON.stringify  (the fix: binds as text, cast parses it)
+ *   - `$N::text[]`                        (the unnest path — arrays bind fine)
+ *   - executeRawJsonb(...)               (passes raw objects, not strings)
+ *   - sql.json(x)                         (postgres.js native jsonb serializer)
+ *   - a `jsonb-guard-ok` comment anywhere in the call span (explicit opt-out)
+ *
+ * Exit 0 = clean, 1 = violations found. Runs under node or bun.
+ */
+import { readdirSync, readFileSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+
+// Default scan roots; overridable via argv so the guard's own test can point it
+// at a fixture dir (e.g. `node check-jsonb-params.mjs /tmp/fixtures`).
+const ROOTS = process.argv.slice(2).length > 0 ? process.argv.slice(2) : ['src', 'scripts'];
+// executeRawDirect must precede executeRaw in the alternation so the longer name
+// wins; executeRawJsonb is deliberately excluded (it passes objects). The
+// optional `<...>` handles generic type args, e.g. `executeRaw<{ id: string }>(`.
+//
+// Only the postgres.js raw path is scanned (executeRaw/executeRawDirect/.unsafe).
+// PGLite's native `this.db.query(...)` is intentionally NOT matched: its driver
+// parses a text→jsonb cast natively, so the double-encode that bites postgres.js
+// `.unsafe()` does not occur there (the `pglite-masks` invariant). The engine
+// parity test pins that the resulting jsonb_typeof agrees across both engines.
+const CALL_RE = /\b(executeRawDirect|executeRaw|unsafe)\s*(?:<[^>;]*>)?\s*\(/g;
+
+/** Walk from the '(' at openIdx and return [start,end) of the balanced span,
+ *  respecting strings, template literals, and comments. */
+function findSpan(src, openIdx) {
+  let depth = 0;
+  let mode = 'code'; // code | line | block | sq | dq | tpl
+  for (let i = openIdx; i < src.length; i++) {
+    const c = src[i];
+    const n = src[i + 1];
+    if (mode === 'line') { if (c === '\n') mode = 'code'; continue; }
+    if (mode === 'block') { if (c === '*' && n === '/') { mode = 'code'; i++; } continue; }
+    if (mode === 'sq') { if (c === '\\') { i++; continue; } if (c === "'") mode = 'code'; continue; }
+    if (mode === 'dq') { if (c === '\\') { i++; continue; } if (c === '"') mode = 'code'; continue; }
+    if (mode === 'tpl') { if (c === '\\') { i++; continue; } if (c === '`') mode = 'code'; continue; }
+    // mode === 'code'
+    if (c === '/' && n === '/') { mode = 'line'; i++; continue; }
+    if (c === '/' && n === '*') { mode = 'block'; i++; continue; }
+    if (c === "'") { mode = 'sq'; continue; }
+    if (c === '"') { mode = 'dq'; continue; }
+    if (c === '`') { mode = 'tpl'; continue; }
+    if (c === '(') depth++;
+    else if (c === ')') { depth--; if (depth === 0) return [openIdx + 1, i]; }
+  }
+  return [openIdx + 1, src.length];
+}
+
+/** Blank out comments so a commented-out example doesn't trip the JSON.stringify probe. */
+function stripComments(s) {
+  return s.replace(/\/\/[^\n]*/g, '').replace(/\/\*[\s\S]*?\*\//g, '');
+}
+
+const violations = [];
+
+function scanFile(file) {
+  const src = readFileSync(file, 'utf8');
+  CALL_RE.lastIndex = 0;
+  let m;
+  while ((m = CALL_RE.exec(src))) {
+    const method = m[1];
+    const openIdx = m.index + m[0].length - 1; // index of the '('
+    const [s, e] = findSpan(src, openIdx);
+    const span = src.slice(s, e);
+    if (/jsonb-guard-ok/.test(span)) continue;
+    if (!/JSON\.stringify\s*\(/.test(stripComments(span))) continue;
+    // A positional `$N::jsonb` that is NOT `$N::text::jsonb`.
+    const jsonbRe = /\$\d+\s*::\s*jsonb\b/g;
+    let j;
+    let badText = '';
+    while ((j = jsonbRe.exec(span))) {
+      const pre = span.slice(Math.max(0, j.index - 12), j.index);
+      if (/::\s*text\s*$/.test(pre)) continue; // $N::text::jsonb is the fix — allowed
+      badText = j[0].replace(/\s+/g, '');
+      break;
+    }
+    if (!badText) continue;
+    const line = src.slice(0, s).split('\n').length;
+    violations.push(
+      `${file}:${line}  ${method}(...) binds JSON.stringify into ${badText} — use $N::text::jsonb or pass a raw object (executeRawJsonb / sql.json)`,
+    );
+  }
+}
+
+function walk(dir) {
+  let ents;
+  try { ents = readdirSync(dir); } catch { return; }
+  for (const ent of ents) {
+    if (ent === 'node_modules') continue;
+    const p = join(dir, ent);
+    const st = statSync(p);
+    if (st.isDirectory()) walk(p);
+    else if (p.endsWith('.ts') && !p.endsWith('.test.ts')) scanFile(p);
+  }
+}
+
+for (const root of ROOTS) walk(root);
+
+if (violations.length) {
+  console.error('JSONB positional double-encode violations (#2339 class):\n');
+  for (const v of violations) console.error('  ' + v);
+  console.error(`\n${violations.length} violation(s). Fix: bind through $N::text::jsonb (keeping JSON.stringify), or pass a raw object via executeRawJsonb / sql.json. See docs/ENGINES.md.`);
+  process.exit(1);
+}
+console.log('check-jsonb-params: clean (no positional $N::jsonb + JSON.stringify double-encodes)');
diff --git a/scripts/check-jsonb-pattern.sh b/scripts/check-jsonb-pattern.sh
index 2403f7b83..d26acb0e2 100755
--- a/scripts/check-jsonb-pattern.sh
+++ b/scripts/check-jsonb-pattern.sh
@@ -44,3 +44,17 @@ if grep -rEn "$MAX_STALLED_PATTERN" src/schema.sql src/core/migrate.ts src/core/
 fi
 
 echo "OK: max_stalled defaults are 5 in all schema sources"
+
+# v0.42.x (#2339 / #2324): positional `$N::jsonb` + JSON.stringify double-encode.
+# The template-string grep above only catches `${JSON.stringify(x)}::jsonb`. It
+# MISSES the positional-param form — executeRaw(`... $N::jsonb ...`,
+# [JSON.stringify(x)]) — which is the exact shape that double-encoded the
+# op_checkpoints pin and aborted every sync in #2339. The AST-lite scanner below
+# catches it. `set -e` propagates its non-zero exit.
+if command -v node >/dev/null 2>&1; then
+  node scripts/check-jsonb-params.mjs
+elif command -v bun >/dev/null 2>&1; then
+  bun scripts/check-jsonb-params.mjs
+else
+  echo "WARN: neither node nor bun on PATH; skipping check-jsonb-params.mjs" >&2
+fi
diff --git a/src/commands/agent.ts b/src/commands/agent.ts
index 4a5ae5500..771c981ac 100644
--- a/src/commands/agent.ts
+++ b/src/commands/agent.ts
@@ -251,7 +251,7 @@ async function runFanout(engine: BrainEngine, queue: MinionQueue, flags: RunFlag
   // do this after submission because each add() returns the committed
   // row's id; the aggregator's seed started with an empty array.
   await engine.executeRaw(
-    `UPDATE minion_jobs SET data = jsonb_set(data, '{children_ids}', $1::jsonb) WHERE id = $2`,
+    `UPDATE minion_jobs SET data = jsonb_set(data, '{children_ids}', $1::text::jsonb) WHERE id = $2`,
     [JSON.stringify(childIds), aggregator.id],
   );
 
diff --git a/src/commands/sources.ts b/src/commands/sources.ts
index e6bac3b37..7e3b26deb 100644
--- a/src/commands/sources.ts
+++ b/src/commands/sources.ts
@@ -692,7 +692,7 @@ async function runFederate(engine: BrainEngine, args: string[], value: boolean):
   const config = parseConfig(src.config);
   config.federated = value;
   await engine.executeRaw(
-    `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+    `UPDATE sources SET config = $1::text::jsonb WHERE id = $2`,
     [JSON.stringify(config), id],
   );
   console.log(`Source "${id}" is now ${value ? 'federated (appears in cross-source default search)' : 'isolated (only searched when explicitly named)'}.`);
@@ -854,7 +854,7 @@ async function runWebhookSet(engine: BrainEngine, args: string[]): Promise<void>
   cfg.webhook_secret = secret;
   cfg.github_repo = githubRepo;
   await engine.executeRaw(
-    `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+    `UPDATE sources SET config = $1::text::jsonb WHERE id = $2`,
     [JSON.stringify(cfg), id],
   );
 
@@ -910,7 +910,7 @@ async function runWebhookRotate(engine: BrainEngine, args: string[]): Promise<vo
   const cfg = parseConfig(src.config);
   cfg.webhook_secret = secret;
   await engine.executeRaw(
-    `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+    `UPDATE sources SET config = $1::text::jsonb WHERE id = $2`,
     [JSON.stringify(cfg), id],
   );
   console.log(`New webhook secret for source "${id}":`);
@@ -934,7 +934,7 @@ async function runWebhookClear(engine: BrainEngine, args: string[]): Promise<voi
   delete cfg.webhook_secret;
   delete cfg.github_repo;
   await engine.executeRaw(
-    `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+    `UPDATE sources SET config = $1::text::jsonb WHERE id = $2`,
     [JSON.stringify(cfg), id],
   );
   console.log(`Webhook configuration cleared for source "${id}".`);
@@ -959,7 +959,7 @@ async function runTrackedBranch(engine: BrainEngine, args: string[]): Promise<vo
   if (setArg) {
     cfg.tracked_branch = setArg;
     await engine.executeRaw(
-      `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+      `UPDATE sources SET config = $1::text::jsonb WHERE id = $2`,
       [JSON.stringify(cfg), id],
     );
     console.log(`Tracked branch for source "${id}" set to "${setArg}".`);
@@ -975,7 +975,7 @@ async function runTrackedBranch(engine: BrainEngine, args: string[]): Promise<vo
       const branch = execFileSync('git', ['-C', src.local_path, 'rev-parse', '--abbrev-ref', 'HEAD'], { encoding: 'utf8' }).trim();
       cfg.tracked_branch = branch;
       await engine.executeRaw(
-        `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+        `UPDATE sources SET config = $1::text::jsonb WHERE id = $2`,
         [JSON.stringify(cfg), id],
       );
       console.log(`Detected branch "${branch}" for source "${id}"; persisted to config.tracked_branch.`);
diff --git a/src/core/chunkers/symbol-resolver.ts b/src/core/chunkers/symbol-resolver.ts
index bd9e56f60..9d1100c85 100644
Binary files a/src/core/chunkers/symbol-resolver.ts and b/src/core/chunkers/symbol-resolver.ts differ
diff --git a/src/core/code-intel/traversal-cache.ts b/src/core/code-intel/traversal-cache.ts
index 5fb732494..59e9ebd1f 100644
--- a/src/core/code-intel/traversal-cache.ts
+++ b/src/core/code-intel/traversal-cache.ts
@@ -123,7 +123,7 @@ export async function putCachedTraversal<T>(
       `INSERT INTO code_traversal_cache
          (symbol_qualified, depth, source_id, response_json,
           max_chunk_updated_at, xmin_max, cluster_generation)
-       VALUES ($1, $2, $3, $4::jsonb, $5::timestamptz, $6, $7)
+       VALUES ($1, $2, $3, $4::text::jsonb, $5::timestamptz, $6, $7)
        ON CONFLICT (symbol_qualified, depth, source_id)
        DO UPDATE SET
          response_json = EXCLUDED.response_json,
diff --git a/src/core/conversation-parser/llm-base.ts b/src/core/conversation-parser/llm-base.ts
index 78d0af205..6671b2cb0 100644
--- a/src/core/conversation-parser/llm-base.ts
+++ b/src/core/conversation-parser/llm-base.ts
@@ -266,13 +266,13 @@ async function writeDbCache<T>(
 ): Promise<void> {
   const [, , contentSha] = splitCacheKey(key);
   if (!contentSha) return;
-  // executeRaw with positional binding for JSONB. Per the sql-query.ts
-  // contract: object values passed via positional params reach the
-  // wire as proper jsonb when cast.
+  // #2339 class: this binds JSON.stringify(value) (a STRING) positionally, so it
+  // must cast through $4::text::jsonb — a bare $4::jsonb double-encodes under
+  // postgres.js .unsafe() (PGLite hides it). Pass a raw object to use $N::jsonb.
   await engine.executeRaw(
     `INSERT INTO conversation_parser_llm_cache
        (content_sha256, model_id, call_shape, value_json)
-     VALUES ($1, $2, $3, $4::jsonb)
+     VALUES ($1, $2, $3, $4::text::jsonb)
      ON CONFLICT (content_sha256, model_id, call_shape) DO NOTHING`,
     [contentSha, modelStr, shape, JSON.stringify(value)],
   );
diff --git a/src/core/cycle/calibration-profile.ts b/src/core/cycle/calibration-profile.ts
index 05aff0234..f07724f48 100644
--- a/src/core/cycle/calibration-profile.ts
+++ b/src/core/cycle/calibration-profile.ts
@@ -356,7 +356,7 @@ class CalibrationProfilePhase extends BaseCyclePhase {
          active_bias_tags, model_id, cost_usd, judge_model_agreement
        ) VALUES ($1, $2, now(), false,
                  $3, $4, $5, $6, $7,
-                 $8::jsonb, $9::text[],
+                 $8::text::jsonb, $9::text[],
                  $10, $11,
                  $12::text[], $13, NULL, NULL)`,
       [
diff --git a/src/core/minions/handlers/subagent.ts b/src/core/minions/handlers/subagent.ts
index fcead52f3..450dc8da0 100644
--- a/src/core/minions/handlers/subagent.ts
+++ b/src/core/minions/handlers/subagent.ts
@@ -878,7 +878,7 @@ async function runSubagentViaGateway(args: GatewayRunArgs): Promise<SubagentResu
       const rows = await engine.executeRaw<{ gbrain_tool_use_id: string }>(
         `INSERT INTO subagent_tool_executions
            (job_id, message_idx, tool_use_id, tool_name, input, status, schema_version, ordinal, gbrain_tool_use_id, provider_id)
-         VALUES ($1, $2, $3, $4, $5::jsonb, 'pending', 2, $6, $7, $8)
+         VALUES ($1, $2, $3, $4, $5::text::jsonb, 'pending', 2, $6, $7, $8)
          ON CONFLICT (job_id, message_idx, ordinal) DO UPDATE
            SET status = subagent_tool_executions.status
          RETURNING gbrain_tool_use_id::text AS gbrain_tool_use_id`,
@@ -891,7 +891,7 @@ async function runSubagentViaGateway(args: GatewayRunArgs): Promise<SubagentResu
     onToolCallComplete: async (gbrainToolUseId, output) => {
       await engine.executeRaw(
         `UPDATE subagent_tool_executions
-           SET status = 'complete', output = $1::jsonb, ended_at = now()
+           SET status = 'complete', output = $1::text::jsonb, ended_at = now()
          WHERE gbrain_tool_use_id::text = $2`,
         [JSON.stringify(output ?? null), gbrainToolUseId],
       );
@@ -1107,7 +1107,7 @@ async function persistMessage(engine: BrainEngine, jobId: number, msg: Persisted
   await engine.executeRaw(
     `INSERT INTO subagent_messages (job_id, message_idx, role, content_blocks,
         tokens_in, tokens_out, tokens_cache_read, tokens_cache_create, model)
-     VALUES ($1, $2, $3, $4::jsonb, $5, $6, $7, $8, $9)
+     VALUES ($1, $2, $3, $4::text::jsonb, $5, $6, $7, $8, $9)
      ON CONFLICT (job_id, message_idx) DO NOTHING`,
     [
       jobId,
@@ -1131,13 +1131,15 @@ async function persistToolExecPending(
   toolName: string,
   input: unknown,
 ): Promise<void> {
-  // Serialize to JSON string for the ::jsonb cast. When `input` is already a
-  // string (e.g. pre-serialized), avoid double-encoding which produces a jsonb
-  // scalar string instead of a jsonb object — breaking `input->>'key'` lookups.
+  // Serialize to a JSON string, then bind through $5::text::jsonb. The value is
+  // ALWAYS a string here (pre-serialized input, or JSON.stringify) — binding a
+  // string to a bare $5::jsonb double-encodes it into a jsonb scalar string under
+  // postgres.js .unsafe() (#2339 class; PGLite hides it). The ::text cast makes
+  // the text→jsonb parse produce a real jsonb object.
   const jsonStr = typeof input === 'string' ? input : JSON.stringify(input);
   await engine.executeRaw(
     `INSERT INTO subagent_tool_executions (job_id, message_idx, tool_use_id, tool_name, input, status)
-     VALUES ($1, $2, $3, $4, $5::jsonb, 'pending')
+     VALUES ($1, $2, $3, $4, $5::text::jsonb, 'pending')
      ON CONFLICT (job_id, tool_use_id) DO NOTHING`,
     [jobId, messageIdx, toolUseId, toolName, jsonStr],
   );
@@ -1151,7 +1153,7 @@ async function persistToolExecComplete(
 ): Promise<void> {
   await engine.executeRaw(
     `UPDATE subagent_tool_executions
-        SET status = 'complete', output = $3::jsonb, ended_at = now()
+        SET status = 'complete', output = $3::text::jsonb, ended_at = now()
       WHERE job_id = $1 AND tool_use_id = $2`,
     [jobId, toolUseId, typeof output === 'string' ? output : JSON.stringify(output)],
   );
@@ -1170,7 +1172,7 @@ async function persistToolExecFailed(
   // rejected upfront) and "pending row exists" (tool threw mid-execute).
   await engine.executeRaw(
     `INSERT INTO subagent_tool_executions (job_id, message_idx, tool_use_id, tool_name, input, status, error, ended_at)
-     VALUES ($1, $2, $3, $4, $5::jsonb, 'failed', $6, now())
+     VALUES ($1, $2, $3, $4, $5::text::jsonb, 'failed', $6, now())
      ON CONFLICT (job_id, tool_use_id) DO UPDATE
        SET status = 'failed', error = EXCLUDED.error, ended_at = now()`,
     [jobId, messageIdx, toolUseId, toolName, typeof input === 'string' ? input : JSON.stringify(input), error],
diff --git a/src/core/onboard/impact-capture.ts b/src/core/onboard/impact-capture.ts
index 7db93a772..f1f622af7 100644
--- a/src/core/onboard/impact-capture.ts
+++ b/src/core/onboard/impact-capture.ts
@@ -120,7 +120,7 @@ export async function writeImpactLogRow(
          remediation_id, metric_name, metric_before, metric_after,
          job_id, source_id, brain_id, started_at, idempotency_key,
          applied_by, details
-       ) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11::jsonb)`,
+       ) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11::text::jsonb)`,
       [
         attribution.remediation_id,
         metricName,
diff --git a/src/core/search/query-cache.ts b/src/core/search/query-cache.ts
index dd68a12e8..6d0558264 100644
--- a/src/core/search/query-cache.ts
+++ b/src/core/search/query-cache.ts
@@ -236,7 +236,7 @@ export class SemanticQueryCache {
       // the v0.40.3.0 IRON-RULE).
       await this.engine.executeRaw(
         `INSERT INTO query_cache (id, query_text, source_id, knobs_hash, embedding, results, meta, ttl_seconds, page_generations, max_generation_at_store, created_at)
-         VALUES ($1, $2, $3, $4, $5::vector, $6::jsonb, $7::jsonb, $8, $9::jsonb, $10, now())
+         VALUES ($1, $2, $3, $4, $5::vector, $6::text::jsonb, $7::text::jsonb, $8, $9::text::jsonb, $10, now())
          ON CONFLICT (id) DO UPDATE SET
            query_text = EXCLUDED.query_text,
            knobs_hash = EXCLUDED.knobs_hash,
diff --git a/src/core/sources-ops.ts b/src/core/sources-ops.ts
index 3cb1c0a9a..a7d95ee77 100644
--- a/src/core/sources-ops.ts
+++ b/src/core/sources-ops.ts
@@ -408,7 +408,7 @@ export async function addSource(
     try {
       await engine.executeRaw(
         `INSERT INTO sources (id, name, local_path, config)
-             VALUES ($1, $2, $3, $4::jsonb)`,
+             VALUES ($1, $2, $3, $4::text::jsonb)`,
         [opts.id, displayName, finalPath, JSON.stringify(config)],
       );
     } catch (e) {
@@ -454,7 +454,7 @@ export async function addSource(
     const displayName = opts.name ?? opts.id;
     await engine.executeRaw(
       `INSERT INTO sources (id, name, local_path, config)
-           VALUES ($1, $2, $3, $4::jsonb)`,
+           VALUES ($1, $2, $3, $4::text::jsonb)`,
       [opts.id, displayName, finalPath, JSON.stringify(config)],
     );
   }
diff --git a/src/core/takes-quality-eval/receipt-write.ts b/src/core/takes-quality-eval/receipt-write.ts
index 5bb77f719..637670dae 100644
--- a/src/core/takes-quality-eval/receipt-write.ts
+++ b/src/core/takes-quality-eval/receipt-write.ts
@@ -32,8 +32,8 @@ export async function writeReceiptToDb(engine: BrainEngine, receipt: TakesQualit
        receipt_json, receipt_disk_path, created_at
      ) VALUES (
        $1, $2, $3, $4,
-       $5, $6, $7, $8::jsonb, $9,
-       $10::jsonb, $11, $12::timestamptz
+       $5, $6, $7, $8::text::jsonb, $9,
+       $10::text::jsonb, $11, $12::timestamptz
      )
      ON CONFLICT (receipt_sha8_corpus, receipt_sha8_prompt, receipt_sha8_models, receipt_sha8_rubric)
      DO NOTHING`,
diff --git a/test/check-jsonb-params.test.ts b/test/check-jsonb-params.test.ts
new file mode 100644
index 000000000..26e1b43ed
--- /dev/null
+++ b/test/check-jsonb-params.test.ts
@@ -0,0 +1,83 @@
+/**
+ * Self-test for scripts/check-jsonb-params.mjs — the positional jsonb
+ * double-encode guard (#2339 / #2324 class). Verifies it catches the bug shape
+ * (including generic-typed calls and the `jsonStr` variable case is acknowledged
+ * as out of scope) and does NOT false-positive on the sanctioned forms.
+ *
+ * Fixtures are written to a temp dir and the scanner is pointed at it via argv,
+ * so this never touches the real src/ tree.
+ */
+import { describe, test, expect, beforeAll, afterAll } from 'bun:test';
+import { mkdtempSync, writeFileSync, mkdirSync, rmSync } from 'node:fs';
+import { join } from 'node:path';
+import { tmpdir } from 'node:os';
+
+const SCRIPT = join(import.meta.dir, '..', 'scripts', 'check-jsonb-params.mjs');
+
+let root: string;
+let badDir: string;
+let goodDir: string;
+
+function runGuard(dir: string): { code: number; err: string } {
+  const res = Bun.spawnSync([process.execPath, SCRIPT, dir]);
+  return { code: res.exitCode, err: res.stderr.toString() + res.stdout.toString() };
+}
+
+beforeAll(() => {
+  root = mkdtempSync(join(tmpdir(), 'jsonb-guard-'));
+  badDir = join(root, 'bad');
+  goodDir = join(root, 'good');
+  mkdirSync(badDir, { recursive: true });
+  mkdirSync(goodDir, { recursive: true });
+
+  // BAD: positional $1::jsonb bound to a JSON.stringify'd value.
+  writeFileSync(
+    join(badDir, 'bad.ts'),
+    "await engine.executeRaw(`INSERT INTO t (a) VALUES ($1::jsonb)`, [JSON.stringify(x)]);\n",
+  );
+  // BAD: generic-typed executeRaw<T>(...) must still be caught.
+  writeFileSync(
+    join(badDir, 'bad_generic.ts'),
+    "await engine.executeRaw<{ id: string }>(`UPDATE t SET a = $2::jsonb WHERE id = $1`, [id, JSON.stringify(x)]);\n",
+  );
+
+  // GOOD: the fix — $1::text::jsonb.
+  writeFileSync(
+    join(goodDir, 'good_text.ts'),
+    "await engine.executeRaw(`INSERT INTO t (a) VALUES ($1::text::jsonb)`, [JSON.stringify(x)]);\n",
+  );
+  // GOOD: text[] array path (the appendCompleted unnest shape).
+  writeFileSync(
+    join(goodDir, 'good_array.ts'),
+    "await engine.executeRaw(`INSERT INTO t (a) SELECT unnest($1::text[])`, [JSON.stringify(arr)]);\n",
+  );
+  // GOOD: executeRawJsonb passes a raw object, not a string — excluded.
+  writeFileSync(
+    join(goodDir, 'good_helper.ts'),
+    "await executeRawJsonb(engine, `INSERT INTO t (a) VALUES ($1::jsonb)`, [], [JSON.stringify(x)]);\n",
+  );
+  // GOOD: explicit opt-out for a rare legitimate object-binding case.
+  writeFileSync(
+    join(goodDir, 'good_optout.ts'),
+    "await engine.executeRaw(`INSERT INTO t (a) VALUES ($1::jsonb)` /* jsonb-guard-ok */, [JSON.stringify(x)]);\n",
+  );
+});
+
+afterAll(() => {
+  rmSync(root, { recursive: true, force: true });
+});
+
+describe('check-jsonb-params guard', () => {
+  test('flags positional $N::jsonb + JSON.stringify (incl. generic-typed calls)', () => {
+    const { code, err } = runGuard(badDir);
+    expect(code).toBe(1);
+    expect(err).toContain('bad.ts');
+    expect(err).toContain('bad_generic.ts');
+  });
+
+  test('passes the sanctioned forms (::text::jsonb, ::text[], executeRawJsonb, opt-out)', () => {
+    const { code, err } = runGuard(goodDir);
+    expect(code).toBe(0);
+    expect(err).toContain('clean');
+  });
+});