Bug: NULL bubble value crashes GET /tabs with TypeError

[bradjin8]

Repository: cppa-cursor-browser
Reported: 2026-05-18
Severity: High

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Summary

Navigating into a project by clicking an item in the "Projects with Conversations" table triggers a GET /api/workspaces/<id>/tabs request that crashes with a 500 error, making the project detail view completely inaccessible.

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Reproduction Steps

1. Run the app locally.
2. Open the main dashboard.
3. Click any project in the "Projects with Conversations" table.
4. Observe a 500 response — the project detail view does not load.

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Error Traceback

GET /api/workspaces/70dab26a3ac44c481f00d49e068473e7 HTTP/1.1" 200 -
Failed to get workspace tabs
Traceback (most recent call last):
  File "api/workspaces.py", line 149, in get_workspace_tabs
    payload, status = assemble_workspace_tabs(workspace_id, workspace_path, rules)
  File "services/workspace_tabs.py", line 101, in assemble_workspace_tabs
    bubble_obj = Bubble.from_dict(json.loads(row["value"]), bubble_id=bid)
TypeError: the JSON object must be str, bytes or bytearray, not NoneType

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Root Cause

In services/workspace_tabs.py, the bubble-loading loop (lines 96–109) queries cursorDiskKV for all bubbleId: keys and immediately calls json.loads(row["value"]) without a None guard:

# services/workspace_tabs.py  lines 96–109
for row in _safe_fetchall("SELECT key, value FROM cursorDiskKV WHERE key LIKE 'bubbleId:%'"):
    parts = row["key"].split(":")
    if len(parts) >= 3:
        bid = parts[2]
        try:
            bubble_obj = Bubble.from_dict(json.loads(row["value"]), bubble_id=bid)  # ← row["value"] can be None
            bubble_map[bid] = bubble_obj.raw
        except SchemaError as e:
            print(f"Schema drift in bubble {bid}: {e}")
        except (json.JSONDecodeError, ValueError):   # ← TypeError is NOT caught
            pass

When a cursorDiskKV row has a NULL value column, row["value"] resolves to None. json.loads(None) raises TypeError, which the current except clause does not handle. The exception propagates up through assemble_workspace_tabs and the API handler returns a 500.

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Acceptance Criteria

• row["value"] is None rows are skipped so a single NULL bubble row cannot crash the tabs endpoint
• GET /api/workspaces/<id>/tabs returns 200 (with the bad row silently skipped) for workspaces containing NULL bubble values
• Fix is covered by a unit test with a mock cursorDiskKV row whose value is NULL / None
• No regression on workspaces without NULL values

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Affected Files

• services/workspace_tabs.py — lines 96–109 (bubble-loading loop)
• api/workspaces.py — line 149 (call site)