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| 1 | +# 5. GUI page registration |
| 2 | + |
| 3 | +Date: 2026-04-08 |
| 4 | + |
| 5 | +## Status |
| 6 | + |
| 7 | +Accepted |
| 8 | + |
| 9 | +## Context |
| 10 | + |
| 11 | +Bridge feature modules (`bridge.home`, `bridge.proscia`, `bridge.hello_world`, `bridge.papi`) |
| 12 | +need to register NiceGUI pages with a frame that displays a consistent header, navigation |
| 13 | +sidebar, and health status bar. The frame function (`bridge.system.gui._frame.frame`) depends |
| 14 | +on `Service().health()` from `bridge.system._service`, making it inherently a system-level |
| 15 | +concern. |
| 16 | + |
| 17 | +The previous implementation created `gui = GUINamespace(frame_func=frame)` in |
| 18 | +`bridge/system/gui/_gui.py` and exported it from `bridge.system`. Feature modules imported |
| 19 | +this singleton via `from bridge.system import gui`. This is a **module boundary violation**: |
| 20 | +feature modules should not depend on the orchestrating system module. |
| 21 | + |
| 22 | +### Alternatives considered |
| 23 | + |
| 24 | +**Option A — Deferred singleton in foundry-core**: Add `gui = GUINamespace()` to |
| 25 | +`aignostics_foundry_core.gui` and a `configure(frame_func=...)` method. Feature modules import |
| 26 | +`gui` from foundry-core; `bridge.system` calls `gui.configure(frame_func=frame)` at startup. |
| 27 | +Rejected: pollutes a generic library with a stateful singleton that must be mutated by the |
| 28 | +application layer. Complicates testing (global state to reset). Philosophically wrong: the |
| 29 | +singleton is bridge-specific and should not live in a general-purpose library. |
| 30 | + |
| 31 | +**Option B — New `bridge.gui` module**: Create `bridge/src/bridge/gui/` as a neutral singleton |
| 32 | +home, independent of `bridge.system`. Feature modules import from `bridge.gui`. |
| 33 | +Rejected: adds a thin wrapper module whose only content is a singleton. The module boundary |
| 34 | +problem is merely moved, not eliminated. No architectural gain justifies the additional module. |
| 35 | + |
| 36 | +**Option C (chosen) — Registry-based page decorators**: The standalone `page_*` decorators in |
| 37 | +foundry-core (`page_authenticated`, `page_public`, etc.) write to a module-level `_registry` |
| 38 | +instead of calling `@ui.page()` immediately. `gui_register_pages(frame_func=frame)` processes |
| 39 | +the registry after all `BasePageBuilder.register_pages()` calls, actualizing each entry with |
| 40 | +the correct `frame_func`. Feature modules import only from `aignostics_foundry_core.gui`. |
| 41 | +`bridge.system` provides the `frame_func` to `gui_run()`, which flows it down to |
| 42 | +`gui_register_pages`. The `gui` singleton in `bridge.system` is deleted entirely. |
| 43 | + |
| 44 | +## Decision |
| 45 | + |
| 46 | +Implement Option C. The standalone `page_*` decorators become pure registration decorators |
| 47 | +that record intent (path, title, access level, page function) to a module-level list. The |
| 48 | +`gui_register_pages(frame_func)` function actualizes all entries using the private |
| 49 | +`_actualize_*` functions. `GUINamespace` methods continue to call `_actualize_*` directly, |
| 50 | +bypassing the registry (preserving the existing opt-in, frame-at-construction-time API for |
| 51 | +any future consumers that prefer it). |
| 52 | + |
| 53 | +`gui_run()` gains a `frame_func` parameter that is forwarded to `gui_register_pages`. |
| 54 | +`bridge.system._service` passes `frame_func=frame` when calling `gui_run()`. |
| 55 | + |
| 56 | +## Consequences |
| 57 | + |
| 58 | +**Easier**: |
| 59 | +- Feature modules have zero dependency on `bridge.system` for page registration. |
| 60 | +- Dependency graph is clean: feature modules → `aignostics_foundry_core.gui`; `bridge.system` |
| 61 | + orchestrates and provides the frame. |
| 62 | +- Adding a new page requires only `from aignostics_foundry_core.gui import page_authenticated` |
| 63 | + — no reference to any singleton or bridge.system. |
| 64 | + |
| 65 | +**Harder / risks**: |
| 66 | +- Page registration is now a two-phase process (write to registry, then actualize). Code that |
| 67 | + calls `page_authenticated(path)(func)` and expects the route to be live immediately (without |
| 68 | + subsequently calling `gui_register_pages`) will silently not register the route. |
| 69 | +- `_registry` is module-level mutable state. Tests must call `clear_page_registry()` in |
| 70 | + teardown to avoid cross-test contamination. |
| 71 | +- `GUINamespace` now calls a different set of internal functions (`_actualize_*`) than the |
| 72 | + public `page_*` API, which is a maintenance surface to keep in sync. |
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