refactor: split large files into submodules (3000-line Rust cap, 2000-line TS cap) + linting enforcement by Copilot · Pull Request #1 · mikenrafter/diff-core

Copilot · 2026-04-23T17:05:11Z

Files exceeding their line-length limits have been split into cohesive submodules while preserving all public interfaces. Linting rules now enforce the caps going forward.

diffcore-core: source modules

Each oversized src/foo.rs becomes src/foo/mod.rs + extracted subfiles. Tests are the dominant contributor in most files — extracted to a sibling tests.rs (or split further when tests alone exceeded the cap).

Before	After
`ast.rs` (3605)	`ast/mod.rs` (1767) · `ast/tests.rs` (1837)
`flow.rs` (3999)	`flow/mod.rs` (1433) · `flow/tests.rs` (2566)
`entrypoint.rs` (3956)	`entrypoint/mod.rs` (2335) · `entrypoint/tests.rs` (1620)
`graph.rs` (4341)	`graph/mod.rs` (1290) · `graph/tests.rs` (1425) · `graph/tests_ir.rs` (1666)

graph needed a second test file because the test section alone was 3071 lines; IR-related test submodules (helper_tests, ir_extends_tests, ir_node_type_tests, edge_case_tests, extended_proptests, workspace_graph_tests) were moved to tests_ir.rs with the three shared test helper functions duplicated there.

diffcore-core: integration tests

tests/e2e_pipeline.rs (3804 lines) was split by language group into six files, each under 900 lines:

e2e_pipeline.rs — core TS/JS/Python/metadata tests (779)
e2e_go_rust.rs — Go + Rust (500)
e2e_jvm.rs — Java + Kotlin + Scala (762)
e2e_csharp_php_ruby.rs — C# + PHP + Ruby (818)
e2e_systems.rs — Swift + C/C++ (536)
e2e_nextjs_large.rs — Next.js + large-diff + staged + config overrides (496)

Each new file carries its own mod helpers; declaration and only the imports it actually uses.

diffcore-tauri: commands module

crates/diffcore-tauri/src/commands.rs (4517 lines) was split into a commands/ directory with 8 focused submodules:

File	Lines	Contents
`commands/mod.rs`	2034	`AppState`, `CommandError`, core analysis commands, shared `pub(super)` helpers, re-exports, tests
`commands/llm.rs`	1054	LLM annotation + refinement streaming commands
`commands/workspace.rs`	339	Git info + workspace file ops (`RepoInfo` struct)
`commands/settings.rs`	279	API keys, LLM config, `LlmSettings` struct
`commands/editor.rs`	274	Editor integration + file-write commands
`commands/comments.rs`	430	Review comment CRUD (private-fn tests co-located)
`commands/manifest.rs`	110	Groups manifest import/export/watch
`commands/app_state.rs`	88	Snapshot persistence

Shared helpers (extract_diff, open_repo, simple_unified_diff, detect_language, load_config_from_path, etc.) live in mod.rs as pub(super) and are called via super:: from submodules. main.rs's generate_handler! was updated to use full module paths (e.g. commands::llm::start_annotate_overview) so Tauri's __cmd__ wrappers resolve correctly.

diffcore-tauri: React UI utility extraction

App.tsx (6685 lines) is being split under the 2000-line cap. Pure utility functions have been extracted from App.tsx (6685 → 5990 lines) into focused modules with no new TypeScript errors:

File	Contents
`src/utils/pathUtils.ts`	`shortPath`, `shortSymbol`, `symbolFilePath`, `parseSymbolEndpoint`, `findLineContainingSymbol`, `truncateSearchResultLine`
`src/utils/gitUtils.ts`	`deriveGitShortStatus`, `resolveFileShortStatus`, `formatBranchStatus`, `formatCompareTargetLabel`, `COMPARE_TARGET_*` constants
`src/utils/activityUtils.ts`	`ActivityKind`, `ActivityPresentation`, `describeActivityEntry`, `buildMockActivityEntries`, `summarizeActivityTimeline`, `providerSupportsToolActivity`, + 12 internal helpers
`src/utils/groupUtils.ts`	`riskLevel`, `getGroupChangeIndicator`, `getFileMovedIndicator`, `computeToolEditHunks`
`src/utils/llmUtils.ts`	`resolveInteractiveProvider`, `resolveInteractiveModel`, `isApiProvider`, `SubscriptionProvider`

Remaining: AppContext provider + panel/tab/modal component split (HeaderBar, LeftPane, CenterPane, RightPane, ActivityTab, AnnotationsTab, CommentsTab, SourceTab, and modals). Architecture and extraction plan documented in specs/component-architecture.md.

Linting

ESLint v9 (flat config) and a Node.js Rust size-check script now enforce both caps. All packages verified CVE-free against the GitHub Advisory Database.

npm run lint — ESLint with:

max-lines: 2000 on all .ts/.tsx source files (test files — *.spec.ts, *.test.ts, etc. — are exempt)
react-hooks/rules-of-hooks and react-hooks/exhaustive-deps
diffcore-local/no-orphan-tauri-commands (see below)

npm run lint:rust-size — scripts/check-rust-file-sizes.js enforces the 3000-line cap across diffcore-core/src/ and diffcore-tauri/src/ (test files exempt). Passes clean.

`no-orphan-tauri-commands` — multi-file comprehension rule

Custom ESLint rule (eslint-rules/no-orphan-tauri-commands.js) that provides cross-language alignment:

At lint-init time it reads all .rs files in crates/diffcore-tauri/src/commands/ and extracts every #[tauri::command] function name.
For every tauriInvoke("cmd_name", ...) call in TypeScript it checks that cmd_name matches a real Rust command. If not, an error is reported on the string literal.
All current tauriInvoke calls validate clean. If the Rust commands directory is unavailable (e.g. UI-only CI), the rule skips gracefully.

Documentation

docs/linting-architecture.md — full rationale: tool choice, CVE verification, size caps, custom rule mechanics, usage instructions, future work
specs/component-architecture.md — target panel/tab/modal structure, AppContext data flow pattern, naming conventions, extraction progress table
specs/readme.md — updated with new spec entry

Original prompt

Files are huge! Let's split things into submodules. ~3000 lines (still bundle docs, tests and prod code together) should be the max. If a file is smaller than that, it's fine. Things should have high cohesion and low coupling. Keep larger module interfaces intact. Functionality should remain the same.

Move the 1847-line test module out of ast.rs into a separate ast/tests.rs file, reducing both files below 3000 lines: - ast/mod.rs: 1767 lines (production code) - ast/tests.rs: 1837 lines (test body) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Converts src/flow.rs (3999 lines) into a module directory to keep individual files below 3000 lines: - flow/mod.rs: production code (1433 lines) - flow/tests.rs: test module body (2566 lines) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

…ts.rs Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

…ests_ir.rs Split 4341-line graph.rs into a module directory: - graph/mod.rs: ~1290 lines of production code + test module declarations - graph/tests.rs: ~1425 lines (first half of tests, through mod ir_proptest) - graph/tests_ir.rs: ~1666 lines (second half with IR-related tests, helper functions duplicated) Both test files are well under the 3000-line limit. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Break up the monolithic e2e_pipeline.rs by language group so every file stays under 3000 lines and is easier to navigate: - e2e_pipeline.rs (779 lines) — core TS/JS/Python/metadata tests - e2e_go_rust.rs (500 lines) — Go and Rust language tests - e2e_jvm.rs (762 lines) — Java, Kotlin, and Scala tests - e2e_csharp_php_ruby.rs(818 lines) — C#, PHP, and Ruby tests - e2e_systems.rs (536 lines) — Swift and C/C++ tests - e2e_nextjs_large.rs (496 lines) — Next.js, large diffs, staged, config and the minimal use imports needed for its tests. All six files compile cleanly with `cargo test --test <name> --no-run`. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

mikenrafter · 2026-04-23T21:34:41Z

@copilot Go ahead and continue with the remaining command.rs refactor.

- commands/mod.rs (2034): AppState, CommandError, core analysis cmds, shared helpers - commands/llm.rs (1057): LLM annotation/refinement commands - commands/workspace.rs (338): git info + workspace file ops - commands/settings.rs (279): API keys + LLM config + LlmSettings struct - commands/editor.rs (274): editor integration + file-write commands - commands/comments.rs (430): review comment CRUD (private fn tests moved here) - commands/manifest.rs (110): groups manifest import/export/watch - commands/app_state.rs (88): snapshot persistence All public interfaces preserved; main.rs updated to use full module paths in generate_handler! so Tauri's __cmd__ wrappers resolve correctly. Agent-Logs-Url: https://github.com/mikenrafter/diff-core/sessions/22a705a7-65f2-4133-8d93-e9e3d306a8ca Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

- Remove duplicate provider_supports_tool_activity from llm.rs, call super:: instead - Move RepoInfo struct before its first use in workspace.rs Agent-Logs-Url: https://github.com/mikenrafter/diff-core/sessions/22a705a7-65f2-4133-8d93-e9e3d306a8ca Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Copilot · 2026-04-23T22:13:58Z

@copilot Go ahead and continue with the remaining command.rs refactor.

Done. commands.rs (4517 lines) is now split into 8 submodules, all under 3000 lines:

File	Lines	Contents
`commands/mod.rs`	2034	AppState, CommandError, core analysis commands, shared `pub(super)` helpers, re-exports, tests
`commands/llm.rs`	1054	LLM annotation/refinement streaming commands
`commands/workspace.rs`	339	Git info + workspace file ops (`RepoInfo` struct at top)
`commands/settings.rs`	279	API keys, LLM config, `LlmSettings` struct
`commands/editor.rs`	274	Editor integration + file-write
`commands/comments.rs`	430	Review comment CRUD (private-fn tests moved here)
`commands/manifest.rs`	110	Groups manifest import/export/watch
`commands/app_state.rs`	88	Snapshot persistence

main.rs generate_handler! updated to use full module paths so Tauri's __cmd__ wrappers resolve correctly. cargo check -p diffcore-tauri passes clean. Committed in 5cb754e.

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mikenrafter · 2026-04-23T22:51:46Z

Great! Now, the react part of the app needs to be made into smaller components. Start with the major UI portions: left pane, right pane, header, center pane. But don't stop there, different tabs need grouping as well. Set the limit for ts files at 2000 lines. Tests in separate .spec.ts files next to them. This all needs to be made into lint rules - keep commands.rs/sub aligned with the ts interface for that and keep the file sizes enforced by the linter. Do not apply size limitations on test files. The lint rules should span both rust and typescript. Ensure the lint library is CVE free and find the one best fit for this purpose. The linting will need to have some variety of multi-file comprehension. @copilot . Leave the totality of your rationale in an explainer .md file. Ensure the spec has detailed and up-to-date details here. Ensure that everything compiles and works well before turning over.

- Create src/utils/ with constants, pathUtils, gitUtils, groupUtils, activityUtils, llmUtils - Create src/hooks/AppContext.tsx with comprehensive AppContextValue interface - Extract JSX sections into: - src/components/CrashTest.tsx - src/components/panels/HeaderBar.tsx - src/components/panels/LeftPane.tsx - src/components/panels/CenterPane.tsx - src/components/panels/RightPane.tsx - src/components/modals/AISetupModal.tsx - src/components/modals/SettingsPanel.tsx - src/components/modals/CommentInputOverlay.tsx - src/components/modals/RegenDialog.tsx - App.tsx now uses AppContext.Provider + component composition - App.tsx reduced from 6685 to ~3530 lines (hooks extraction pending) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

This reverts commit 5bae1a1. Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Agent-Logs-Url: https://github.com/mikenrafter/diff-core/sessions/13839a79-bcad-4e97-ad33-0275757c5339 Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

mikenrafter · 2026-04-23T23:47:23Z

Continue work on the utility extraction and move forward with the linting plan. Ensure you keep the spec detailed and updated. @copilot

…add docs and spec Agent-Logs-Url: https://github.com/mikenrafter/diff-core/sessions/ec403341-0eff-4b49-9ee0-49b3f9c7b722 Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Copilot · 2026-04-23T23:57:03Z

Continue work on the utility extraction and move forward with the linting plan. Ensure you keep the spec detailed and updated. @copilot

Done in cd2329b. Here's what was completed:

Utility extraction from App.tsx (6685 → 5990 lines, zero new TS errors):

src/utils/pathUtils.ts — path/symbol helpers
src/utils/gitUtils.ts — git status helpers + COMPARE_TARGET_* constants + formatCompareTargetLabel
src/utils/activityUtils.ts — ActivityKind, ActivityPresentation, describeActivityEntry, buildMockActivityEntries, summarizeActivityTimeline, + 12 more helpers
src/utils/groupUtils.ts — riskLevel, getGroupChangeIndicator, getFileMovedIndicator, computeToolEditHunks
src/utils/llmUtils.ts — resolveInteractiveProvider, resolveInteractiveModel, SubscriptionProvider

Linting (CVE-free packages confirmed against GitHub Advisory DB):

eslint.config.js — ESLint v9 flat config; max-lines: 2000 on all .ts/.tsx (test files exempt); react-hooks rules
eslint-rules/no-orphan-tauri-commands.js — custom multi-file rule: reads all #[tauri::command] fn names from crates/diffcore-tauri/src/commands/*.rs and errors on any tauriInvoke("cmd") call that has no matching Rust command. All current tauriInvoke calls validate clean.
scripts/check-rust-file-sizes.js — 3000-line Rust cap; npm run lint:rust-size passes clean
package.json gains lint and lint:rust-size scripts

Docs & spec:

docs/linting-architecture.md — full rationale (tool choice, CVE check, size caps, custom rule mechanics, how to run)
specs/component-architecture.md — target structure, extraction progress table, AppContext data flow, naming conventions
specs/readme.md updated

The max-lines error on App.tsx (5990 lines) is intentional — it tracks remaining work. The panel/tab/modal split (HeaderBar, LeftPane, CenterPane, RightPane, ActivityTab, AnnotationsTab, CommentsTab, SourceTab, modals) via an AppContext provider is the next phase, detailed in the spec.

Initial plan

acb1a58

Copilot AI assigned Copilot and mikenrafter Apr 23, 2026

Copilot started work on behalf of mikenrafter April 23, 2026 17:05 View session

Copilot AI and others added 5 commits April 23, 2026 17:21

refactor: split entrypoint.rs into entrypoint/mod.rs + entrypoint/tes…

ba2e402

…ts.rs Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Refactor large files into submodules for better organization~~ refactor: split large files into submodules (3000-line cap) Apr 23, 2026

Copilot finished work on behalf of mikenrafter April 23, 2026 18:01

Copilot AI requested a review from mikenrafter April 23, 2026 18:01

Copilot started work on behalf of mikenrafter April 23, 2026 21:34 View session

Copilot AI and others added 2 commits April 23, 2026 22:09

Copilot finished work on behalf of mikenrafter April 23, 2026 22:14

Copilot started work on behalf of mikenrafter April 23, 2026 22:51 View session

Copilot AI and others added 3 commits April 23, 2026 23:39

Revert "refactor: extract App.tsx into components and hooks (phase 2)"

4f9404d

This reverts commit 5bae1a1. Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

refactor: begin utility extraction from App.tsx (pathUtils, gitUtils)

083bd98

Agent-Logs-Url: https://github.com/mikenrafter/diff-core/sessions/13839a79-bcad-4e97-ad33-0275757c5339 Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Copilot AI changed the title ~~refactor: split large files into submodules (3000-line cap)~~ refactor: split large files into submodules (3000-line Rust cap, 2000-line TS cap) Apr 23, 2026

Copilot finished work on behalf of mikenrafter April 23, 2026 23:44

Copilot started work on behalf of mikenrafter April 23, 2026 23:47 View session

feat: extract App.tsx utils, add ESLint with command-alignment rule, …

cd2329b

…add docs and spec Agent-Logs-Url: https://github.com/mikenrafter/diff-core/sessions/ec403341-0eff-4b49-9ee0-49b3f9c7b722 Co-authored-by: mikenrafter <88250914+mikenrafter@users.noreply.github.com>

Copilot AI changed the title ~~refactor: split large files into submodules (3000-line Rust cap, 2000-line TS cap)~~ refactor: split large files into submodules (3000-line Rust cap, 2000-line TS cap) + linting enforcement Apr 23, 2026

Copilot finished work on behalf of mikenrafter April 23, 2026 23:58

mikenrafter added 3 commits April 23, 2026 23:00

Made minor adjustments before continuing code relocation...

780846a

Another large batch of App.tsx extraction

1211a13

Basic refactor finished

6a747d9

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refactor: split large files into submodules (3000-line Rust cap, 2000-line TS cap) + linting enforcement - #1

refactor: split large files into submodules (3000-line Rust cap, 2000-line TS cap) + linting enforcement#1
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diffcore-core: source modules

diffcore-core: integration tests

diffcore-tauri: commands module

diffcore-tauri: React UI utility extraction

Linting

no-orphan-tauri-commands — multi-file comprehension rule

Documentation

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