Experiment: Event Sourcing #100

pragmatrix · 2026-02-06T15:23:02Z

I suspect that the complexities of typed hierarchies is too much for me and there must be a simpler way. In this PR I took some inspiration from event sourcing to experiment with a systems / aggregate approach that - in the end - may result in a fully incremental system that is overall simpler to understand, easier to maintain, and supports adding cross-cutting features without to much accidental complexity.

Copilot

Pull request overview

Introduces an event-sourced “system/aggregate” approach for the desktop UI, refactoring intent handling into command transactions and aggregating layout/state updates centrally.

Changes:

Added DesktopSystem + supporting Cmd/Transaction primitives to apply commands and update UI effects.
Refactored desktop/project/launcher interaction flow to return commands instead of UserIntent.
Updated massive_layout API (padding and child/nesting naming) and broadened re-exports in a couple of modules.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
shell/src/application_context.rs	Small formatting-only change around animation cycle upgrade call.
layout/src/lib.rs	Switches to wildcard re-exports for layout public API.
layout/src/layouter.rs	Renames `children` → `nested`, updates builder API (`padding`), adds `Thickness` conversions, updates tests accordingly.
layout/src/dimensional_types.rs	Adds `Thickness` conversion from `(Padding, Padding)` and imports `Padding` from crate.
desktop/src/projects/project_presenter.rs	Introduces `ProjectCommand`; shifts presenter transitions to return `Cmd` and updates layout construction calls.
desktop/src/projects/project.rs	Splits `LaunchGroup` into `properties` + `contents`; introduces `LaunchGroupProperties`.
desktop/src/projects/mod.rs	Switches to wildcard re-exports for the projects module API.
desktop/src/projects/launcher_presenter.rs	Returns `Cmd`, emits `DesktopCommand` on launcher interactions, returns insertion index on present.
desktop/src/lib.rs	Adds new modules (`aggregates`, `desktop_system`, `event_sourcing`) and re-exports aggregates.
desktop/src/event_sourcing/mod.rs	Adds `Cmd` and `Transaction` primitives and composition ops for event-sourcing style updates.
desktop/src/desktop_system.rs	New `DesktopSystem` aggregate applying commands, managing hierarchy/layout specs, and updating effects.
desktop/src/desktop_presenter.rs	Refactors event forwarding to return `Cmd`; exposes `apply_layout`; adjusts layout building for `nested`.
desktop/src/desktop_interaction.rs	Replaces `UserIntent` with `Cmd`/`DesktopCommand` and updates keyboard preprocessing.
desktop/src/desktop.rs	Replaces presenter/interaction wiring with `DesktopSystem` and routes commands via `transact` + `update_effects`.
desktop/src/band_presenter.rs	Removes special-case “present primary instance”; returns insertion index; updates layout to use `nested`.
desktop/src/aggregates/ordered_hierarchy.rs	New ordered hierarchy aggregate with add/insert/remove and unit tests.
desktop/src/aggregates/mod.rs	New aggregates module exports.
desktop/src/aggregates/layout_specs.rs	New small `Map` wrapper with typed erroring remove and indexing.
.github/copilot-instructions.md	Adds guidance to prefer failing on unexpected states over silent defensive handling.

layout/src/lib.rs

desktop/src/projects/mod.rs

layout/src/layouter.rs

Copilot · 2026-02-12T07:22:13Z

layout/src/dimensional_types.rs


 use derive_more::{From, Index, IndexMut, Into};

+use crate::Padding;


This introduces a dependency from dimensional_types back to Padding (which appears to live in the layouter side), increasing module coupling in a place that otherwise looks like a low-level geometry/types module. Consider moving this From<(Padding, Padding)> for Thickness impl into layouter.rs (or colocating Padding with the other dimensional types) to keep dimensional_types independent of higher-level layout concerns.

Copilot · 2026-02-12T07:22:13Z

layout/src/dimensional_types.rs

+impl<const RANK: usize> From<(Padding<RANK>, Padding<RANK>)> for Thickness<RANK> {
+    fn from((leading, trailing): (Padding<RANK>, Padding<RANK>)) -> Self {
+        Self {
+            leading: leading.into(),
+            trailing: trailing.into(),
+        }
+    }
+}


This introduces a dependency from dimensional_types back to Padding (which appears to live in the layouter side), increasing module coupling in a place that otherwise looks like a low-level geometry/types module. Consider moving this From<(Padding, Padding)> for Thickness impl into layouter.rs (or colocating Padding with the other dimensional types) to keep dimensional_types independent of higher-level layout concerns.

Copilot · 2026-02-12T07:22:14Z

desktop/src/desktop_system.rs

+            ProjectCommand::AddLauncher {
+                group,
+                id,
+                profile: _,
+            } => {
+                let target = DesktopTarget::Launcher(id);
+                self.hierarchy.add(group.into(), target.clone())?;
+                self.layout_specs
+                    .insert_or_update(target, self.default_panel_size);
+            }


The profile payload in ProjectCommand::AddLauncher is currently ignored (profile: _). That makes the command misleading as an event-sourcing primitive (it appears to carry the data required to apply the change, but the system drops it). Either remove profile from the command if it’s intentionally unused by the system state, or store/apply it (e.g., update the corresponding presenter/project aggregate) so replaying commands reconstructs all necessary state.

Copilot · 2026-02-12T07:22:14Z

desktop/src/event_sourcing/mod.rs

+    #[allow(non_upper_case_globals)]
+    pub const None: Self = Self(Vec::new());


Using a non-UPPERCASE associated constant requires suppressing non_upper_case_globals, which is a sign the API is fighting Rust naming conventions. Consider replacing this with a conventional pub const NONE: Self = ... or a pub fn none() -> Self constructor to avoid the lint suppression while keeping call sites readable.

Suggested change

#[allow(non_upper_case_globals)]

pub const None: Self = Self(Vec::new());

pub const NONE: Self = Self(Vec::new());

desktop/src/aggregates/ordered_hierarchy.rs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

pragmatrix changed the title ~~First rudimentary implementation of the DesktopSystem~~ Experiment: First rudimentary implementation of the DesktopSystem Feb 6, 2026

pragmatrix changed the title ~~Experiment: First rudimentary implementation of the DesktopSystem~~ Experiment: Event Sourcing Feb 6, 2026

pragmatrix force-pushed the event-sourcing branch from 4a21c13 to 26186e6 Compare February 6, 2026 15:23

pragmatrix added 3 commits February 6, 2026 16:42

es: First rudimentary implementation of the DesktopSystem

02c03c5

es: Size the launchers

bf8e3cd

es: Integrate DesktopSystem as a stand-in for DesktopPresenter

03a2adc

pragmatrix force-pushed the event-sourcing branch from f9720e9 to 03a2adc Compare February 6, 2026 15:42

pragmatrix added 7 commits February 6, 2026 16:45

es: Clippy

8f4d59a

Simplify OrderedHierarchy, remove OrderedInsertion

526b1fb

Remove OrderedInsertion

08085e1

Review OrderedHierarchy

ade56a1

es: Add add_nested

e329102

Simplify

e8770d7

No need to support a function to present the primary instance anymore

06c83e2

pragmatrix force-pushed the event-sourcing branch from ea00522 to 06c83e2 Compare February 7, 2026 07:22

pragmatrix added 8 commits February 7, 2026 11:03

es: Make event sourced layout working

e90ca7f

es: Move interaction into the DesktopSystem

a317d02

Clippy

fe7990f

es: Implement present_instance

56579e5

es: Add PresentView

4c6a980

es: Present the initial terminal through a transaction

217a431

Replace user intent by Cmd and re-implement the commands

ed587d2

New use format

471813d

pragmatrix requested a review from Copilot February 12, 2026 07:18

Copilot AI reviewed Feb 12, 2026

View reviewed changes

pragmatrix and others added 5 commits February 12, 2026 08:23

Update desktop/src/aggregates/ordered_hierarchy.rs

aba4fc5

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Naming

fb74db5

es: Set instance rects inside the launchers

dc9dddb

es: Clippy and remove unused layout functions

0c85f4f

es: Cleanup imports

5637b4d

pragmatrix added 4 commits February 12, 2026 16:26

es: Directly resolve layout specs

794cfa4

Remove instances from the hierarchy when they are gone

5d6497e

Line

b9fc2c7

Remove commented code

3dc47ca

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Experiment: Event Sourcing #100

Experiment: Event Sourcing #100

Uh oh!

pragmatrix commented Feb 6, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI Feb 12, 2026

Uh oh!

Copilot AI Feb 12, 2026

Uh oh!

Copilot AI Feb 12, 2026

Uh oh!

Copilot AI Feb 12, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant


		use derive_more::{From, Index, IndexMut, Into};

		use crate::Padding;

		#[allow(non_upper_case_globals)]
		pub const None: Self = Self(Vec::new());

Experiment: Event Sourcing #100

Are you sure you want to change the base?

Experiment: Event Sourcing #100

Uh oh!

Conversation

pragmatrix commented Feb 6, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI Feb 12, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 12, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 12, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 12, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant