Module Map

This part explains how the documented packages are implemented and how to extend them, using concepts and public interfaces. This chapter is its map: which source modules each package has, what each one is responsible for, and which direction its dependencies point. It defines no interfaces of its own — it names the files that implement the interfaces defined in the earlier parts.

How a package is organized

Every package has one entry file in its repository root, named after the package: etaf.el, ebox.el, ecss.el, ekp.el, etaf-ui.el and etaf-db.el. The entry adds the package's lisp/ directory to load-path, loads the implementation modules in a fixed order, and owns the authoritative Commentary. A program adds the repository root to load-path and requires the entry; it never requires a file under lisp/. Ecosystem and Layers states the rule and its consequence: a feature and a symbol that the entry Commentary does not list are internal, even without a double hyphen.

The modules below lisp/ are private implementation files. This chapter describes what they are responsible for, not what they contain: their symbols, data structures and internal functions are outside the manual, and the tables give no way to call them. A module name can change in any release, so nothing outside the package should depend on the division.

The tables read as follows. Module is the file path in the repository. Responsibility is the kind of work the module owns. Depends on lists the modules the file loads directly, limited to the documented packages; Emacs's own libraries and modules that are loaded indirectly are not repeated. Dependencies point downward: a module may load a lower layer or a module in its own layer that is closer to the bottom, never a higher one. Each package's docs/architecture.md explains the rationale of its division in more detail.

The ECSS modules

Module	Responsibility	Depends on
lisp/ecss-selector.el	Selector parsing, matching and specificity	—
lisp/ecss-cascade.el	Style schemas, cascade and computed values	lisp/ecss-selector.el
lisp/ecss-file.el	Reading .ecss rule files into the structures the cascade consumes	lisp/ecss-cascade.el

The selector module is the bottom of the package: it knows nothing about styles or rules. The cascade module uses it to match rules and owns the schema, the origins and the computation of values. The file module is a reader on top: it turns source text into rules and hands them to the cascade. This is the smallest module set of all packages and the one every other package builds on.

The Ebox modules

Module	Responsibility	Depends on
lisp/ebox-size.el	Validation and resolution of (unit number) lengths and size functions	—
lisp/ebox-measure.el	Pixel measurement, text-unit segmentation, display spaces and display twins	—
lisp/ebox-style.el	Style schema, aliases, validators, shorthand expansion and ECSS scopes	lisp/ebox-size.el, ECSS
lisp/ebox-node.el	Retained node records, author properties, the selector adapter and computed styles	lisp/ebox-measure.el, lisp/ebox-size.el, lisp/ebox-style.el, ECSS
lisp/ebox-image.el	Image preparation, the converter protocol and the raster cache	lisp/ebox-measure.el
lisp/ebox-layout.el	Text, box, row, column and positioned layout, line composition and edit planning	lisp/ebox-node.el, lisp/ebox-image.el
lisp/ebox-flex.el	The flex and grid algorithms	lisp/ebox-node.el, lisp/ebox-size.el, lisp/ebox-layout.el
lisp/ebox-buffer.el	Mounts, the dirty queue, flush orchestration, buffer writes and geometry queries	lisp/ebox-node.el, lisp/ebox-layout.el, lisp/ebox-flex.el
lisp/ebox-interaction.el	Keymaps, focus, activation, drag, input sessions and scrolling	lisp/ebox-node.el, lisp/ebox-layout.el, lisp/ebox-buffer.el
lisp/ebox-viewport.el	The window-size bridge and settled refit scheduling	lisp/ebox-buffer.el
lisp/ebox-file.el	.ebox source reading, companion loading and preview	lisp/ebox-node.el

The two pure modules at the top of the table — sizes and measurement — do not know about nodes, mounts or buffers. Nodes depend on them and on styles; layout depends on nodes and images; the mount layer depends on nodes and layout. Interaction is layered above mounted buffers, and the viewport bridge above the mount layer only requests a refit. One deliberate soft cycle deserves a note: the layout module calls the flex and grid algorithms through forward declarations and the entry loads the layout module before the flex module, so the large layout core does not have to load the flex and grid details it dispatches to.

The ETAF modules

ETAF has the largest module set. Its core is the authoring model; the Runtime is the hub that ties the model to Ebox; the remaining modules are capabilities layered on the Runtime.

Module	Responsibility	Depends on
lisp/etaf-view.el	The structural View language shared by Hosts and Components	Ebox
lisp/etaf-compiler.el	Compiling supported topology into embedded blueprints	lisp/etaf-view.el
lisp/etaf-reactive.el	The reactive graph: refs, computeds, effects and Scopes	—
lisp/etaf-component.el	Component definitions, instances, bindings and setup	lisp/etaf-view.el, lisp/etaf-compiler.el, lisp/etaf-reactive.el, ECSS
lisp/etaf-context.el	The inherited provide/inject environment	lisp/etaf-reactive.el
lisp/etaf-behavior.el	Reusable Behavior bundles of semantic attributes and setup	lisp/etaf-reactive.el
lisp/etaf-controlled-behavior.el	Controlled Behavior variants for application-owned geometry	lisp/etaf-behavior.el
lisp/etaf-observer.el	The observation port scoped to one dynamic operation	—
lisp/etaf-runtime.el	Mounting, the retained segment tree, commits and Host maps	lisp/etaf-view.el, lisp/etaf-component.el, lisp/etaf-reactive.el, lisp/etaf-behavior.el, lisp/etaf-context.el, lisp/etaf-observer.el, Ebox
lisp/etaf-events.el	Runtime event entry points into Host callbacks	lisp/etaf-runtime.el, lisp/etaf-reactive.el, Ebox
lisp/etaf-actions.el	Named Actions and their dispatch	lisp/etaf-runtime.el, lisp/etaf-reactive.el
lisp/etaf-keys.el	Host key tables, help and hint keys	lisp/etaf-runtime.el, lisp/etaf-events.el, lisp/etaf-regions.el, lisp/etaf-reactive.el, Ebox
lisp/etaf-regions.el	Region declarations and region navigation	lisp/etaf-runtime.el, lisp/etaf-events.el, Ebox
lisp/etaf-viewport.el	Nested viewport regions and settled refit	lisp/etaf-runtime.el, lisp/etaf-component.el, lisp/etaf-events.el
lisp/etaf-async.el	The asynchronous operation shared by Resource and Data	lisp/etaf-reactive.el
lisp/etaf-resource.el	Loaded resource values and their cleanup	lisp/etaf-async.el, lisp/etaf-observer.el, lisp/etaf-reactive.el
lisp/etaf-data.el	The reactive data controller over explicit source capabilities	lisp/etaf-async.el, lisp/etaf-observer.el, lisp/etaf-reactive.el
lisp/etaf-list-cache.el	The stale-while-revalidate list cache	—
lisp/etaf-animation.el	Time-driven refs for transitions and animations	lisp/etaf-reactive.el
lisp/etaf-performance.el	The optional performance recorder	lisp/etaf-runtime.el
lisp/etaf-video-source.el	Video source normalization, probing and frame filtering	—
lisp/etaf-video-audio.el	The audio sidecar of a playback session	lisp/etaf-video-source.el
lisp/etaf-video-session.el	The playback session: frame producer, sidecar and timer	lisp/etaf-video-source.el, lisp/etaf-video-audio.el
lisp/etaf-video-component.el	The etaf-video Component	lisp/etaf-video-source.el, lisp/etaf-video-session.el, lisp/etaf-video-audio.el, lisp/etaf-component.el, lisp/etaf-reactive.el, lisp/etaf-runtime.el

The Runtime is required by every capability module and requires none of them, which is what makes Actions, keys, regions, viewport regions and the performance recorder optional layers rather than parts of the core. The video modules form their own small stack: source, audio sidecar, session and finally the Component. The entry loads all of them, so requiring etaf loads the whole framework.

The EKP modules

Module	Responsibility	Depends on
lisp/ekp-utils.el	Font handling, measurement helpers and the native module build and load	—
lisp/ekp-hyphen.el	Liang hyphenation patterns and dictionaries	—
lisp/ekp-layout.el	The box, glue and penalty model, the break search, layout and rendering	lisp/ekp-utils.el, lisp/ekp-hyphen.el
lisp/ekp-buffer.el	Interactive region and buffer justification and the auto mode	lisp/ekp-layout.el

EKP is independent of the other packages: its two bottom modules are pure and its layout module is the only user of them. The buffer module is the interactive handle: region and buffer commands, the minor mode, protected regions and diagnostics all live there. Implementation describes the pipeline these modules implement.

The catalog and storage packages

The component catalog is divided by component family. Most families load the basic module, which owns the simple controls and the shared style conventions; the icon, input, selection, surface, table and navigation families build on it, and the advanced, media and reactions modules compose those. The storage package is one module that registers a Data backend.

Module	Responsibility	Depends on
lisp/etaf-ui-style.el	Shared style helpers and the theme token defaults	ETAF
lisp/etaf-ui-svg.el	SVG parsing helpers used by the icon family	—
lisp/etaf-ui-basic.el	etaf-label, etaf-button, etaf-checkbox and etaf-panel	lisp/etaf-ui-style.el
lisp/etaf-ui-icon.el	etaf-ui-icon and the icon set	lisp/etaf-ui-basic.el
lisp/etaf-ui-feedback.el	Badge, divider, progress, alert, statistic, empty, skeleton, card, avatar, timeline, tag and kbd	lisp/etaf-ui-basic.el
lisp/etaf-ui-selection.el	Radio, switch, segmented, slider and range	lisp/etaf-ui-basic.el
lisp/etaf-ui-input.el	Menu, select and number input	lisp/etaf-ui-basic.el
lisp/etaf-ui-field.el	Text input and search field	lisp/etaf-ui-basic.el, lisp/etaf-ui-icon.el, lisp/etaf-ui-input.el
lisp/etaf-ui-editor.el	Embedded native editor helpers	—
lisp/etaf-ui-surface.el	Popover, dialog, tooltip, toast, dropdown menu, context menu and drawer	lisp/etaf-ui-feedback.el, lisp/etaf-ui-icon.el, lisp/etaf-ui-input.el, Ebox
lisp/etaf-ui-navigation.el	Tabs, accordion, breadcrumb and steps	lisp/etaf-ui-basic.el
lisp/etaf-ui-table.el	Table and list	lisp/etaf-ui-basic.el
lisp/etaf-ui-data.el	Data grid and pagination	lisp/etaf-ui-table.el
lisp/etaf-ui-advanced.el	Date picker, tree, calendar and command palette	lisp/etaf-ui-input.el, lisp/etaf-ui-navigation.el, lisp/etaf-ui-surface.el, lisp/etaf-ui-table.el
lisp/etaf-ui-media.el	Media viewer	lisp/etaf-ui-icon.el, lisp/etaf-ui-selection.el, lisp/etaf-ui-surface.el
lisp/etaf-ui-reactions.el	Reactions	lisp/etaf-ui-icon.el, lisp/etaf-ui-surface.el
lisp/etaf-ui-desktop.el	Taskbar, workspace bar, launcher, switcher, splitter and pane resizer	lisp/etaf-ui-basic.el, lisp/etaf-ui-style.el, lisp/etaf-ui-surface.el
lisp/etaf-ui-window.el	Window chrome, window controls and resizable panel	lisp/etaf-ui-basic.el
lisp/etaf-ui-tile-grid.el	Tile grid	lisp/etaf-ui-basic.el
lisp/etaf-ui-text-grid.el	Text grid	lisp/etaf-ui-basic.el
lisp/etaf-ui-playing-card.el	Playing card	lisp/etaf-ui-basic.el
lisp/etaf-sqlite-store.el	The SQLite Data source	ETAF, Emacs's sqlite support

The catalog's three helpers that need a fact the engine measures — the viewport size used to size a surface or a field, the input commands a field must forward, and the pixel width a selection helper compares — read that fact from Ebox's public viewport and measurement interfaces rather than copying the measurement. Every other catalog dependency goes to ETAF.

Keeping the map accurate

This map is descriptive. The supported interfaces remain those in each entry file's Commentary, and Public interfaces defines what that means for consumers. When a package adds, splits, merges or moves a module, the change updates this chapter and the package's docs/architecture.md in the same delivery, because both describe the same division from different readers' points of view: this chapter the whole ecosystem at a glance, the package document the rationale of one package.