Add standalone P&ID designer app by aahilsyed72 · Pull Request #2 · calstar/STAR

aahilsyed72 · 2026-06-03T06:12:01Z

Extracts P&ID designer from EngineDesign into its own top-level app at pid-designer/. Includes:

FastAPI backend on port 8001 with git-backed diagram persistence (load, autosave, checkpoint, history, version restore)
React/Vite frontend on port 5174 with pan/select modes, undo/redo, branching edges, fluid type coloring, and draggable labels
dev.sh to start both services with one command

Note

Medium Risk
Large new surface area; checkpoint/pull endpoints invoke real git commit/push/pull on the host repo, which can surprise users or fail without credentials even though scope is isolated under pid-designer/.

Overview
Adds a new top-level pid-designer/ app extracted from EngineDesign: a React + Vite + XYFlow editor and a FastAPI service on port 8001, with dev.sh to run both and a path-scoped GitHub Actions workflow (frontend tsc/build, backend import check).

The backend persists diagrams to diagrams/pid_main.json and exposes /api/pid/* for load, debounced autosave, git pull, checkpoint (add/commit/push), commit history, and version restore via git show.

The UI adds a component palette, pan/select, undo/redo, rotation, branchable edges (click-to-junction), edge fluid-type coloring, draggable/editable labels, JSON import/export, and toolbar flows for checkpoint, history, and get-latest.

Vite proxies /api to 8001; the frontend dev server uses port 5174.

^{Reviewed by Cursor Bugbot for commit bb732d8. Bugbot is set up for automated code reviews on this repo. Configure here.}

Extracts P&ID designer from EngineDesign into its own top-level app at pid-designer/. Includes: - FastAPI backend on port 8001 with git-backed diagram persistence (load, autosave, checkpoint, history, version restore) - React/Vite frontend on port 5174 with pan/select modes, undo/redo, branching edges, fluid type coloring, and draggable labels - dev.sh to start both services with one command Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cursor · 2026-06-03T06:13:04Z

+
+  const onMouseMove = useCallback((e: React.MouseEvent<SVGGElement>) => {
+    const svg = (e.currentTarget as SVGElement).closest('svg');
+    if (!svg || !pathRef.current) return;


Branching edge mouse guard

High Severity

onMouseMove returns immediately because it requires pathRef.current, but no path element ever receives that ref. The branch preview dot never appears and clicks cannot split edges, so advertised branching on pipes does not work.

^{Reviewed by Cursor Bugbot for commit 609b0a5. Configure here.}

cursor · 2026-06-03T06:13:04Z

+      }).catch(() => {});
+    }, 1000);
+    return () => clearTimeout(t);
+  }, [nodes, edges]);


Autosave overwrites before load

High Severity

The canvas starts empty and schedules autosave one second after every nodes/edges change, without waiting for /api/pid/load. If load is slow, fails, or the backend errors, autosave can POST an empty diagram and overwrite pid_main.json on disk.

^{Reviewed by Cursor Bugbot for commit 609b0a5. Configure here.}

cursor · 2026-06-03T06:13:04Z

+}
+
+let _idCounter = 1;
+const genId = () => `node_${_idCounter++}`;


Node id counter resets

High Severity

New nodes use genId() from a module-level counter that always starts at 1 on page load. After loading a saved diagram that already contains node_1, node_3, etc., the next dropped component can reuse an existing id and break React Flow state.

Additional Locations (1)

pid-designer/frontend/src/components/pid/PIDDesigner.tsx#L236-L237

^{Reviewed by Cursor Bugbot for commit 609b0a5. Configure here.}

- Use plain NodeProps (no generic) in all node components — @xyflow/react v12 changed the NodeProps generic signature - Remove sourceHandle/targetHandle from BranchableEdge destructure — not on EdgeProps in v12 - Fix unused 'i' variable in PIDToolbar history map - Remove missing @types/node from tsconfig.node.json Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cursor · 2026-06-03T06:26:01Z

+            continue
+        parts = line.split("|", 2)
+        if len(parts) == 3:
+            entries.append({"hash": parts[0], "title": parts[1], "timestamp": parts[2]})


History breaks on pipe titles

Medium Severity

History lines join hash, subject, and ISO time with |, then split with split("|", 2). Checkpoint titles containing | produce wrong titles and timestamps in the History UI and confuse restore labels.

^{Reviewed by Cursor Bugbot for commit cd9402f. Configure here.}

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

This reverts commit 8dd4212.

cursor · 2026-06-03T06:34:18Z

+      index.current = history.current.length - 1;
+    }, 300);
+    return () => { if (timer.current) clearTimeout(timer.current); };
+  }, [nodes, edges]);


Undo restores empty canvas

Medium Severity

Undo history is seeded with an empty snapshot and is not reset after a successful load, so one undo after opening the designer can clear the entire diagram.

Additional Locations (1)

pid-designer/frontend/src/components/pid/PIDDesigner.tsx#L121-L129

^{Reviewed by Cursor Bugbot for commit d0e413f. Configure here.}

cursor · 2026-06-03T06:34:18Z

+    };
+    window.addEventListener('keydown', handler);
+    return () => window.removeEventListener('keydown', handler);
+  }, [setNodes]);


Shortcuts fire while typing

Medium Severity

Global keydown handlers for rotate (R), pan (V), and box select (B) do not ignore events when focus is in an input or textarea, so typing in labels or checkpoint fields triggers canvas actions.

Additional Locations (1)

pid-designer/frontend/src/components/pid/PIDToolbar.tsx#L50-L66

^{Reviewed by Cursor Bugbot for commit d0e413f. Configure here.}

cursor · 2026-06-03T06:34:18Z

+
+GIT_ROOT = _git_root()
+# Path used in `git show <hash>:<path>` — must be relative to the git repo root.
+GIT_DIAGRAM_PATH = str(DIAGRAM_PATH.relative_to(GIT_ROOT))


Git root resolved at import

Medium Severity

_git_root() ignores git exit status and module-level GIT_DIAGRAM_PATH is computed at import; a failed rev-parse can make router import crash or break version restore paths.

^{Reviewed by Cursor Bugbot for commit d0e413f. Configure here.}

cursor · 2026-06-03T06:34:19Z

+@router.get("/load")
+async def load_diagram():
+    """Load the current diagram from disk."""
+    return _read_diagram()


Load crashes on bad JSON

Medium Severity

_read_diagram calls json.loads without handling decode errors, so a corrupted pid_main.json causes /api/pid/load to return an unhandled 500 instead of a safe fallback.

^{Reviewed by Cursor Bugbot for commit d0e413f. Configure here.}

Runs on changes to pid-designer/** — two jobs: TypeScript build (npm run build) and backend import check (pip install + python3 -c "import backend.main"). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cursor

Cursor Bugbot has reviewed your changes using default effort and found 2 potential issues.

There are 10 total unresolved issues (including 8 from previous reviews).

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 64b27b5. Configure here.}

cursor · 2026-06-03T06:37:56Z

+      }).catch(() => {});
+    }, 1000);
+    return () => clearTimeout(t);
+  }, [nodes, edges]);


Autosave can wipe diagram

High Severity

Autosave runs on the initial empty canvas and again after undo to the seeded empty snapshot, persisting { nodes: [], edges: [] } over pid_main.json if load is slow or the user undoes once.

^{Reviewed by Cursor Bugbot for commit 64b27b5. Configure here.}

cursor · 2026-06-03T06:37:56Z

+        _run_git("commit", "-m", commit_message)
+        _run_git("push")
+    except RuntimeError as e:
+        raise HTTPException(status_code=500, detail=f"git operation failed: {e}")


Checkpoint fails unchanged file

Medium Severity

After autosave has already written the same JSON, git commit often has nothing to commit and the checkpoint endpoint returns 500 even though the diagram on disk is current.

^{Reviewed by Cursor Bugbot for commit 64b27b5. Configure here.}

requirements.txt was reverted; install fastapi/uvicorn/pydantic inline. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cursor Bot reviewed Jun 3, 2026

View reviewed changes

Aahil syed and others added 2 commits June 2, 2026 23:31

Add backend requirements.txt and auto-install in dev.sh

8dd4212

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

Revert "Add backend requirements.txt and auto-install in dev.sh"

d0e413f

This reverts commit 8dd4212.

cursor Bot reviewed Jun 3, 2026

View reviewed changes

Add GitHub Actions CI workflow for P&ID Designer

64b27b5

Runs on changes to pid-designer/** — two jobs: TypeScript build (npm run build) and backend import check (pip install + python3 -c "import backend.main"). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cursor Bot reviewed Jun 3, 2026

View reviewed changes

Fix CI backend step: inline pip deps instead of requirements.txt

bb732d8

requirements.txt was reverted; install fastapi/uvicorn/pydantic inline. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

aahilsyed72 merged commit 2358600 into main Jun 3, 2026
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Add standalone P&ID designer app#2

Add standalone P&ID designer app#2
aahilsyed72 merged 6 commits into
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feat/pid-designer-standalone

aahilsyed72 commented Jun 3, 2026 •

edited by cursor Bot

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aahilsyed72 commented Jun 3, 2026 • edited by cursor Bot Loading Uh oh! There was an error while loading. Please reload this page.

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Branching edge mouse guard

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Autosave overwrites before load

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Node id counter resets

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History breaks on pipe titles

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Undo restores empty canvas

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Shortcuts fire while typing

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Git root resolved at import

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Load crashes on bad JSON

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Autosave can wipe diagram

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Checkpoint fails unchanged file

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aahilsyed72 commented Jun 3, 2026 •

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