From ff9c87bfc793306531673e5d6fdea39de25dfabf Mon Sep 17 00:00:00 2001
From: mptyl <mp@tylconsulting.it>
Date: Tue, 11 Aug 2026 19:58:28 +0200
Subject: [PATCH] chore: expose DWH preprocessing failure detail under P2 debug

---
 backend/scripts/p2-acceptance.mjs | 1 +
 harness/tht/cli/preprocess_cmd.py | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/backend/scripts/p2-acceptance.mjs b/backend/scripts/p2-acceptance.mjs
index 340267cf..d0613680 100644
--- a/backend/scripts/p2-acceptance.mjs
+++ b/backend/scripts/p2-acceptance.mjs
@@ -781,6 +781,7 @@ async function writeInstallationFiles(ctx) {
         image: ctx.coreImageTag,
         environment: {
           P2_CHILD_DEBUG: "1",
+          THT_P2_DEBUG: "1",
           THT_EVIDENCE_PRIVATE_HOST_ALLOWLIST: "host.docker.internal",
         },
         extra_hosts: ["host.docker.internal:host-gateway"],
diff --git a/harness/tht/cli/preprocess_cmd.py b/harness/tht/cli/preprocess_cmd.py
index 3bd008c6..a716fa50 100644
--- a/harness/tht/cli/preprocess_cmd.py
+++ b/harness/tht/cli/preprocess_cmd.py
@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import hashlib
 import json
+import os
 import re
 from pathlib import Path
 
@@ -259,8 +260,10 @@ def dwh_cmd(
         raise typer.Exit(code=2)
     try:
         result = run_dwh_from_config(config, steps=selected, resume=resume)
-    except Exception:  # noqa: BLE001
+    except Exception as exc:  # noqa: BLE001
         payload = {"status": "failed", "error": "DWH preprocessing failed"}
+        if os.environ.get("THT_P2_DEBUG") == "1":
+            payload["error"] = f"DWH preprocessing failed: {type(exc).__name__}: {exc}"
         if json_output:
             typer.echo(json.dumps(payload, sort_keys=True))
         else: