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1076/**
* App Router file-system routing.
*
* Scans the app/ directory following Next.js App Router conventions:
* - app/page.tsx -> /
* - app/about/page.tsx -> /about
* - app/blog/[slug]/page.tsx -> /blog/:slug
* - app/[...catchAll]/page.tsx -> /:catchAll+
* - app/route.ts -> / (API route)
* - app/(group)/page.tsx -> / (route groups are transparent)
* - Layouts: app/layout.tsx wraps all children
* - Loading: app/loading.tsx -> Suspense fallback
* - Error: app/error.tsx -> ErrorBoundary
* - Not Found: app/not-found.tsx
*/
import path from "node:path";
import fs from "node:fs";
import { glob } from "node:fs/promises";
export interface InterceptingRoute {
/** The interception convention: "." | ".." | "../.." | "..." */
convention: string;
/** The URL pattern this intercepts (e.g. "/photos/:id") */
targetPattern: string;
/** Absolute path to the intercepting page component */
pagePath: string;
/** Parameter names for dynamic segments */
params: string[];
}
export interface ParallelSlot {
/** Slot name (e.g. "team" from @team) */
name: string;
/** Absolute path to the slot's page component */
pagePath: string | null;
/** Absolute path to the slot's default.tsx fallback */
defaultPath: string | null;
/** Absolute path to the slot's layout component (wraps slot content) */
layoutPath: string | null;
/** Absolute path to the slot's loading component */
loadingPath: string | null;
/** Absolute path to the slot's error component */
errorPath: string | null;
/** Intercepting routes within this slot */
interceptingRoutes: InterceptingRoute[];
/**
* The layout index (0-based, in route.layouts[]) that this slot belongs to.
* Slots are passed as props to the layout at their directory level, not
* necessarily the innermost layout. -1 means "innermost" (legacy default).
*/
layoutIndex: number;
}
export interface AppRoute {
/** URL pattern, e.g. "/" or "/about" or "/blog/:slug" */
pattern: string;
/** Absolute file path to the page component */
pagePath: string | null;
/** Absolute file path to the route handler (route.ts) */
routePath: string | null;
/** Ordered list of layout files from root to leaf */
layouts: string[];
/** Ordered list of template files from root to leaf (parallel to layouts) */
templates: string[];
/** Parallel route slots (from @slot directories at the route's directory level) */
parallelSlots: ParallelSlot[];
/** Loading component path */
loadingPath: string | null;
/** Error component path (leaf directory only) */
errorPath: string | null;
/**
* Per-layout error boundary paths, aligned with the layouts array.
* Each entry is the error.tsx at the same directory level as the
* corresponding layout (or null if that level has no error.tsx).
* Used to interleave ErrorBoundary components with layouts so that
* ancestor error boundaries catch errors from descendant segments.
*/
layoutErrorPaths: (string | null)[];
/** Not-found component path (nearest, walking up from page dir) */
notFoundPath: string | null;
/**
* Not-found component paths per layout level (aligned with layouts array).
* Each entry is the not-found.tsx at that layout's directory, or null.
* Used to create per-layout NotFoundBoundary so that notFound() thrown from
* a layout is caught by the parent layout's boundary (matching Next.js behavior).
*/
notFoundPaths: (string | null)[];
/** Forbidden component path (403) */
forbiddenPath: string | null;
/** Unauthorized component path (401) */
unauthorizedPath: string | null;
/**
* URL segment depth for each layout in the layouts array.
* Used by useSelectedLayoutSegments() to determine which segments are
* below a given layout. For example, root layout has depth 0, a layout
* at app/dashboard/ has depth 1 (one URL segment: "dashboard").
* Route groups and parallel slots don't contribute to the depth.
*/
layoutSegmentDepths: number[];
/** Whether this is a dynamic route */
isDynamic: boolean;
/** Parameter names for dynamic segments */
params: string[];
}
// Cache for app routes
let cachedRoutes: AppRoute[] | null = null;
let cachedAppDir: string | null = null;
export function invalidateAppRouteCache(): void {
cachedRoutes = null;
cachedAppDir = null;
}
/**
* Scan the app/ directory and return a list of routes.
*/
export async function appRouter(appDir: string): Promise<AppRoute[]> {
if (cachedRoutes && cachedAppDir === appDir) return cachedRoutes;
// Find all page.tsx and route.ts files, excluding @slot directories
// (slot pages are not standalone routes — they're rendered as props of their parent layout)
const routes: AppRoute[] = [];
// Process page files in a single pass
for await (const file of glob("**/page.{tsx,ts,jsx,js}", { cwd: appDir, exclude: ["**/@*"] })) {
const route = fileToAppRoute(file, appDir, "page");
if (route) routes.push(route);
}
// Process route handler files (API routes) in a single pass
for await (const file of glob("**/route.{tsx,ts,jsx,js}", { cwd: appDir, exclude: ["**/@*"] })) {
const route = fileToAppRoute(file, appDir, "route");
if (route) routes.push(route);
}
// Discover sub-routes created by nested pages within parallel slots.
// In Next.js, pages nested inside @slot directories create additional URL routes.
// For example, @audience/demographics/page.tsx at app/parallel-routes/ creates
// a route at /parallel-routes/demographics.
const slotSubRoutes = discoverSlotSubRoutes(routes, appDir);
routes.push(...slotSubRoutes);
// Sort: static routes first, then dynamic, then catch-all
routes.sort((a, b) => {
const diff = routePrecedence(a.pattern) - routePrecedence(b.pattern);
return diff !== 0 ? diff : a.pattern.localeCompare(b.pattern);
});
cachedRoutes = routes;
cachedAppDir = appDir;
return routes;
}
/**
* Discover sub-routes created by nested pages within parallel slots.
*
* In Next.js, pages nested inside @slot directories create additional URL routes.
* For example, given:
* app/parallel-routes/@audience/demographics/page.tsx
* This creates a route at /parallel-routes/demographics where:
* - children slot → parent's default.tsx
* - @audience slot → @audience/demographics/page.tsx (matched)
* - other slots → their default.tsx (fallback)
*/
function discoverSlotSubRoutes(
routes: AppRoute[],
_appDir: string,
): AppRoute[] {
const syntheticRoutes: AppRoute[] = [];
const existingPatterns = new Set(routes.map((r) => r.pattern));
for (const parentRoute of routes) {
if (parentRoute.parallelSlots.length === 0) continue;
if (!parentRoute.pagePath) continue;
const parentPageDir = path.dirname(parentRoute.pagePath);
// Collect sub-paths from all slots.
// Map: relative sub-path (e.g., "demographics") -> Map<slotName, pagePath>
const subPathMap = new Map<string, Map<string, string>>();
for (const slot of parentRoute.parallelSlots) {
const slotDir = path.join(parentPageDir, `@${slot.name}`);
if (!fs.existsSync(slotDir)) continue;
const subPages = findSlotSubPages(slotDir);
for (const { relativePath, pagePath } of subPages) {
if (!subPathMap.has(relativePath)) {
subPathMap.set(relativePath, new Map());
}
subPathMap.get(relativePath)!.set(slot.name, pagePath);
}
}
if (subPathMap.size === 0) continue;
// Find the default.tsx for the children slot at the parent directory
const childrenDefault = findFile(parentPageDir, "default");
for (const [subPath, slotPages] of subPathMap) {
// Convert sub-path segments to URL pattern parts
const subSegments = subPath.split(path.sep);
const urlParts: string[] = [];
const subParams: string[] = [];
let subIsDynamic = false;
for (const seg of subSegments) {
// Route groups are transparent
if (seg.startsWith("(") && seg.endsWith(")")) continue;
const catchAllMatch = seg.match(/^\[\.\.\.([\w-]+)\]$/);
if (catchAllMatch) {
subIsDynamic = true;
subParams.push(catchAllMatch[1]);
urlParts.push(`:${catchAllMatch[1]}+`);
continue;
}
const optionalCatchAllMatch = seg.match(/^\[\[\.\.\.([\w-]+)\]\]$/);
if (optionalCatchAllMatch) {
subIsDynamic = true;
subParams.push(optionalCatchAllMatch[1]);
urlParts.push(`:${optionalCatchAllMatch[1]}*`);
continue;
}
const dynamicMatch = seg.match(/^\[([\w-]+)\]$/);
if (dynamicMatch) {
subIsDynamic = true;
subParams.push(dynamicMatch[1]);
urlParts.push(`:${dynamicMatch[1]}`);
continue;
}
urlParts.push(seg);
}
const subUrlPath = urlParts.join("/");
const pattern =
parentRoute.pattern === "/"
? "/" + subUrlPath
: parentRoute.pattern + "/" + subUrlPath;
// Skip if this pattern already exists as a regular route
if (existingPatterns.has(pattern)) continue;
if (syntheticRoutes.some((r) => r.pattern === pattern)) continue;
// Build parallel slots for this sub-route: matching slots get the sub-page,
// non-matching slots get null pagePath (rendering falls back to defaultPath)
const subSlots: ParallelSlot[] = parentRoute.parallelSlots.map(
(slot) => ({
...slot,
pagePath: slotPages.get(slot.name) || null,
}),
);
syntheticRoutes.push({
pattern,
pagePath: childrenDefault, // children slot uses parent's default.tsx as page
routePath: null,
layouts: parentRoute.layouts,
templates: parentRoute.templates,
parallelSlots: subSlots,
loadingPath: parentRoute.loadingPath,
errorPath: parentRoute.errorPath,
layoutErrorPaths: parentRoute.layoutErrorPaths,
notFoundPath: parentRoute.notFoundPath,
notFoundPaths: parentRoute.notFoundPaths,
forbiddenPath: parentRoute.forbiddenPath,
unauthorizedPath: parentRoute.unauthorizedPath,
layoutSegmentDepths: parentRoute.layoutSegmentDepths,
isDynamic: parentRoute.isDynamic || subIsDynamic,
params: [...parentRoute.params, ...subParams],
});
}
}
return syntheticRoutes;
}
/**
* Find all page files in subdirectories of a parallel slot directory.
* Returns relative paths (from the slot dir) and absolute page paths.
* Skips the root page.tsx (already handled as the slot's main page)
* and intercepting route directories.
*/
function findSlotSubPages(
slotDir: string,
): Array<{ relativePath: string; pagePath: string }> {
const results: Array<{ relativePath: string; pagePath: string }> = [];
function scan(dir: string): void {
if (!fs.existsSync(dir)) return;
const entries = fs.readdirSync(dir, { withFileTypes: true });
for (const entry of entries) {
if (!entry.isDirectory()) continue;
// Skip intercepting route directories
if (matchInterceptConvention(entry.name)) continue;
// Skip private folders (prefixed with _)
if (entry.name.startsWith("_")) continue;
const subDir = path.join(dir, entry.name);
const page = findFile(subDir, "page");
if (page) {
const relativePath = path.relative(slotDir, subDir);
results.push({ relativePath, pagePath: page });
}
// Continue scanning deeper for nested sub-pages
scan(subDir);
}
}
scan(slotDir);
return results;
}
/**
* Convert a file path relative to app/ into an AppRoute.
*/
function fileToAppRoute(
file: string,
appDir: string,
type: "page" | "route",
): AppRoute | null {
// Remove the filename (page.tsx or route.ts)
const dir = path.dirname(file);
const segments = dir === "." ? [] : dir.split(path.sep);
const params: string[] = [];
let isDynamic = false;
// Convert segments to URL pattern, stripping route groups and parallel slots
const urlSegments: string[] = [];
for (const segment of segments) {
// Route groups: (group) -> skip (transparent in URL)
if (segment.startsWith("(") && segment.endsWith(")")) {
continue;
}
// Parallel slots: @slot -> skip (invisible in URL, content passed as layout props)
if (segment.startsWith("@")) {
continue;
}
// Catch-all: [...slug] (param names may contain hyphens, e.g. [...sign-in])
const catchAllMatch = segment.match(/^\[\.\.\.([\w-]+)\]$/);
if (catchAllMatch) {
isDynamic = true;
params.push(catchAllMatch[1]);
urlSegments.push(`:${catchAllMatch[1]}+`);
continue;
}
// Optional catch-all: [[...slug]] (param names may contain hyphens, e.g. [[...sign-in]])
const optionalCatchAllMatch = segment.match(/^\[\[\.\.\.([\w-]+)\]\]$/);
if (optionalCatchAllMatch) {
isDynamic = true;
params.push(optionalCatchAllMatch[1]);
urlSegments.push(`:${optionalCatchAllMatch[1]}*`);
continue;
}
// Dynamic segment: [id] (param names may contain hyphens, e.g. [my-param])
const dynamicMatch = segment.match(/^\[([\w-]+)\]$/);
if (dynamicMatch) {
isDynamic = true;
params.push(dynamicMatch[1]);
urlSegments.push(`:${dynamicMatch[1]}`);
continue;
}
try {
urlSegments.push(decodeURIComponent(segment));
} catch {
urlSegments.push(segment);
}
}
const pattern = "/" + urlSegments.join("/");
// Discover layouts and templates from root to leaf
const layouts = discoverLayouts(segments, appDir);
const templates = discoverTemplates(segments, appDir);
// Compute the URL segment depth for each layout.
// Each layout corresponds to a directory level. We need to count how many
// of the filesystem segments up to that layout's level contribute URL segments
// (i.e., are not route groups or parallel slots).
const layoutSegmentDepths = computeLayoutSegmentDepths(
segments,
appDir,
layouts,
);
// Discover per-layout error boundaries (aligned with layouts array).
// In Next.js, each segment independently wraps its children with an ErrorBoundary.
// This array enables interleaving error boundaries with layouts in the rendering.
const layoutErrorPaths = discoverLayoutAlignedErrors(segments, appDir);
// Discover loading, error in the route's directory
const routeDir = dir === "." ? appDir : path.join(appDir, dir);
const loadingPath = findFile(routeDir, "loading");
const errorPath = findFile(routeDir, "error");
// Discover not-found/forbidden/unauthorized: walk from route directory up to root (nearest wins).
const notFoundPath = discoverBoundaryFile(segments, appDir, "not-found");
const forbiddenPath = discoverBoundaryFile(segments, appDir, "forbidden");
const unauthorizedPath = discoverBoundaryFile(
segments,
appDir,
"unauthorized",
);
// Discover per-layout not-found files (one per layout directory).
// These are used for per-layout NotFoundBoundary to match Next.js behavior where
// notFound() thrown from a layout is caught by the parent layout's boundary.
const notFoundPaths = discoverBoundaryFilePerLayout(layouts, "not-found");
// Discover parallel slots (@team, @analytics, etc.).
// Slots at the route's own directory use page.tsx; slots at ancestor directories
// (inherited from parent layouts) use default.tsx as fallback.
const parallelSlots = discoverInheritedParallelSlots(
segments,
appDir,
routeDir,
);
return {
pattern: pattern === "/" ? "/" : pattern,
pagePath: type === "page" ? path.join(appDir, file) : null,
routePath: type === "route" ? path.join(appDir, file) : null,
layouts,
templates,
parallelSlots,
loadingPath,
errorPath,
layoutErrorPaths,
notFoundPath,
notFoundPaths,
forbiddenPath,
unauthorizedPath,
layoutSegmentDepths,
isDynamic,
params,
};
}
/**
* Compute the URL segment depth for each layout in the layouts array.
* Root layout = 0, then each directory level that contributes a URL segment
* increments the depth. Route groups and parallel slots don't contribute.
*/
function computeLayoutSegmentDepths(
segments: string[],
appDir: string,
layouts: string[],
): number[] {
// Build a map: layout file path → depth in URL segments
// Walk the segments directory-by-directory, tracking cumulative URL depth
const depthMap = new Map<string, number>();
// Root layout (at appDir) always has depth 0
const rootLayout = findFile(appDir, "layout");
if (rootLayout) depthMap.set(rootLayout, 0);
let urlDepth = 0;
let currentDir = appDir;
for (const segment of segments) {
currentDir = path.join(currentDir, segment);
// Count URL-visible segments (skip route groups and parallel slots)
const isRouteGroup = segment.startsWith("(") && segment.endsWith(")");
const isParallelSlot = segment.startsWith("@");
if (!isRouteGroup && !isParallelSlot) {
urlDepth++;
}
const layout = findFile(currentDir, "layout");
if (layout) {
depthMap.set(layout, urlDepth);
}
}
// Map the ordered layouts array to their depths
return layouts.map((layoutPath) => depthMap.get(layoutPath) ?? 0);
}
/**
* Discover all layout files from root to the given directory.
* Each level of the directory tree may have a layout.tsx.
*/
function discoverLayouts(segments: string[], appDir: string): string[] {
const layouts: string[] = [];
// Check root layout
const rootLayout = findFile(appDir, "layout");
if (rootLayout) layouts.push(rootLayout);
// Check each directory level
let currentDir = appDir;
for (const segment of segments) {
currentDir = path.join(currentDir, segment);
const layout = findFile(currentDir, "layout");
if (layout) layouts.push(layout);
}
return layouts;
}
/**
* Discover all template files from root to the given directory.
* Each level of the directory tree may have a template.tsx.
* Templates are like layouts but re-mount on navigation.
*/
function discoverTemplates(segments: string[], appDir: string): string[] {
const templates: string[] = [];
// Check root template
const rootTemplate = findFile(appDir, "template");
if (rootTemplate) templates.push(rootTemplate);
// Check each directory level
let currentDir = appDir;
for (const segment of segments) {
currentDir = path.join(currentDir, segment);
const template = findFile(currentDir, "template");
if (template) templates.push(template);
}
return templates;
}
/**
* Discover error.tsx files aligned with the layouts array.
* Walks the same directory levels as discoverLayouts and, for each level
* that contributes a layout entry, checks whether error.tsx also exists.
* Returns an array of the same length as discoverLayouts() would return,
* with the error path (or null) at each corresponding layout level.
*
* This enables interleaving ErrorBoundary components with layouts in the
* rendering tree, matching Next.js behavior where each segment independently
* wraps its children with an error boundary.
*/
function discoverLayoutAlignedErrors(
segments: string[],
appDir: string,
): (string | null)[] {
const errors: (string | null)[] = [];
// Root level (only if root has a layout — matching discoverLayouts logic)
const rootLayout = findFile(appDir, "layout");
if (rootLayout) {
errors.push(findFile(appDir, "error"));
}
// Check each directory level
let currentDir = appDir;
for (const segment of segments) {
currentDir = path.join(currentDir, segment);
const layout = findFile(currentDir, "layout");
if (layout) {
errors.push(findFile(currentDir, "error"));
}
}
return errors;
}
/**
* Discover the nearest boundary file (not-found, forbidden, unauthorized)
* by walking from the route's directory up to the app root.
* Returns the first (closest) file found, or null.
*/
function discoverBoundaryFile(
segments: string[],
appDir: string,
fileName: string,
): string | null {
// Build all directory paths from leaf to root
const dirs: string[] = [];
let dir = appDir;
dirs.push(dir);
for (const segment of segments) {
dir = path.join(dir, segment);
dirs.push(dir);
}
// Walk from leaf (last) to root (first)
for (let i = dirs.length - 1; i >= 0; i--) {
const f = findFile(dirs[i], fileName);
if (f) return f;
}
return null;
}
/**
* Discover boundary files (not-found, forbidden, unauthorized) at each layout directory.
* Returns an array aligned with the layouts array, where each entry is the boundary
* file at that layout's directory, or null if none exists there.
*
* This is used for per-layout error boundaries. In Next.js, each layout level
* has its own boundary that wraps the layout's children. When notFound() is thrown
* from a layout, it propagates up to the parent layout's boundary.
*/
function discoverBoundaryFilePerLayout(
layouts: string[],
fileName: string,
): (string | null)[] {
return layouts.map((layoutPath) => {
const layoutDir = path.dirname(layoutPath);
return findFile(layoutDir, fileName);
});
}
/**
* Discover parallel slots inherited from ancestor directories.
*
* In Next.js, parallel slots belong to the layout that defines them. When a
* child route is rendered, its parent layout's slots must still be present.
* If the child doesn't have matching content in a slot, the slot's default.tsx
* is rendered instead.
*
* Walk from appDir through each segment to the route's directory. At each level
* that has @slot dirs, collect them. Slots at the route's own directory level
* use page.tsx; slots at ancestor levels use default.tsx only.
*/
function discoverInheritedParallelSlots(
segments: string[],
appDir: string,
routeDir: string,
): ParallelSlot[] {
const slotMap = new Map<string, ParallelSlot>();
// Walk from appDir through each segment, tracking layout indices.
// layoutIndex tracks which position in the route's layouts[] array corresponds
// to a given directory. Only directories with a layout.tsx file increment.
let currentDir = appDir;
const dirsToCheck: { dir: string; layoutIdx: number }[] = [];
let layoutIdx = findFile(appDir, "layout") ? 0 : -1;
dirsToCheck.push({ dir: appDir, layoutIdx: Math.max(layoutIdx, 0) });
for (const segment of segments) {
currentDir = path.join(currentDir, segment);
if (findFile(currentDir, "layout")) {
layoutIdx++;
}
dirsToCheck.push({ dir: currentDir, layoutIdx: Math.max(layoutIdx, 0) });
}
for (const { dir, layoutIdx: lvlLayoutIdx } of dirsToCheck) {
const isOwnDir = dir === routeDir;
const slotsAtLevel = discoverParallelSlots(dir, appDir);
for (const slot of slotsAtLevel) {
if (isOwnDir) {
// At the route's own directory: use page.tsx (normal behavior)
slot.layoutIndex = lvlLayoutIdx;
slotMap.set(slot.name, slot);
} else {
// At an ancestor directory: use default.tsx as the page, not page.tsx
// (the slot's page.tsx is for the parent route, not this child route)
const inheritedSlot: ParallelSlot = {
...slot,
pagePath: null, // Don't use ancestor's page.tsx
layoutIndex: lvlLayoutIdx,
// defaultPath, loadingPath, errorPath, interceptingRoutes remain
};
// Only inherit if we haven't seen this slot at a closer level
if (!slotMap.has(slot.name)) {
slotMap.set(slot.name, inheritedSlot);
}
}
}
}
return Array.from(slotMap.values());
}
/**
* Discover parallel route slots (@team, @analytics, etc.) in a directory.
* Returns a ParallelSlot for each @-prefixed subdirectory that has a page or default component.
*/
function discoverParallelSlots(dir: string, appDir: string): ParallelSlot[] {
if (!fs.existsSync(dir)) return [];
const entries = fs.readdirSync(dir, { withFileTypes: true });
const slots: ParallelSlot[] = [];
for (const entry of entries) {
if (!entry.isDirectory() || !entry.name.startsWith("@")) continue;
const slotName = entry.name.slice(1); // "@team" -> "team"
const slotDir = path.join(dir, entry.name);
const pagePath = findFile(slotDir, "page");
const defaultPath = findFile(slotDir, "default");
const interceptingRoutes = discoverInterceptingRoutes(slotDir, dir, appDir);
// Only include slots that have at least a page, default, or intercepting route
if (!pagePath && !defaultPath && interceptingRoutes.length === 0) continue;
slots.push({
name: slotName,
pagePath,
defaultPath,
layoutPath: findFile(slotDir, "layout"),
loadingPath: findFile(slotDir, "loading"),
errorPath: findFile(slotDir, "error"),
interceptingRoutes,
layoutIndex: -1, // Will be set by discoverInheritedParallelSlots
});
}
return slots;
}
/**
* The interception convention prefix patterns.
* (.) — same level, (..) — one level up, (..)(..)" — two levels up, (...) — root
*/
const INTERCEPT_PATTERNS = [
{ prefix: "(...)", convention: "..." },
{ prefix: "(..)(..)", convention: "../.." },
{ prefix: "(..)", convention: ".." },
{ prefix: "(.)", convention: "." },
] as const;
/**
* Discover intercepting routes inside a parallel slot directory.
*
* Intercepting routes use conventions like (.)photo, (..)feed, (...), etc.
* They intercept navigation to another route and render within the slot instead.
*
* @param slotDir - The parallel slot directory (e.g. app/feed/@modal)
* @param routeDir - The directory of the route that owns this slot (e.g. app/feed)
* @param appDir - The root app directory
*/
function discoverInterceptingRoutes(
slotDir: string,
routeDir: string,
appDir: string,
): InterceptingRoute[] {
if (!fs.existsSync(slotDir)) return [];
const results: InterceptingRoute[] = [];
// Recursively scan for page files inside intercepting directories
scanForInterceptingPages(slotDir, routeDir, appDir, results);
return results;
}
/**
* Recursively scan a directory tree for page.tsx files that are inside
* intercepting route directories.
*/
function scanForInterceptingPages(
currentDir: string,
routeDir: string,
appDir: string,
results: InterceptingRoute[],
): void {
if (!fs.existsSync(currentDir)) return;
const entries = fs.readdirSync(currentDir, { withFileTypes: true });
for (const entry of entries) {
if (!entry.isDirectory()) continue;
// Check if this directory name starts with an interception convention
const interceptMatch = matchInterceptConvention(entry.name);
if (interceptMatch) {
// This directory is the start of an intercepting route
// e.g. "(.)photos" means intercept same-level "photos" route
const restOfName = entry.name.slice(interceptMatch.prefix.length);
const interceptDir = path.join(currentDir, entry.name);
// Find page files within this intercepting directory tree
collectInterceptingPages(
interceptDir,
interceptDir,
interceptMatch.convention,
restOfName,
routeDir,
appDir,
results,
);
} else {
// Regular subdirectory — keep scanning for intercepting dirs
scanForInterceptingPages(
path.join(currentDir, entry.name),
routeDir,
appDir,
results,
);
}
}
}
/**
* Match a directory name against interception convention prefixes.
*/
function matchInterceptConvention(
name: string,
): { prefix: string; convention: string } | null {
for (const pattern of INTERCEPT_PATTERNS) {
if (name.startsWith(pattern.prefix)) {
return pattern;
}
}
return null;
}
/**
* Collect page.tsx files inside an intercepting route directory tree
* and compute their target URL patterns.
*/
function collectInterceptingPages(
currentDir: string,
interceptRoot: string,
convention: string,
interceptSegment: string,
routeDir: string,
appDir: string,
results: InterceptingRoute[],
): void {
// Check for page.tsx in current directory
const page = findFile(currentDir, "page");
if (page) {
const targetPattern = computeInterceptTarget(
convention,
interceptSegment,
currentDir,
interceptRoot,
routeDir,
appDir,
);
if (targetPattern) {
results.push({
convention,
targetPattern: targetPattern.pattern,
pagePath: page,
params: targetPattern.params,
});
}
}
// Recurse into subdirectories for nested intercepting routes
if (!fs.existsSync(currentDir)) return;
const entries = fs.readdirSync(currentDir, { withFileTypes: true });
for (const entry of entries) {
if (!entry.isDirectory()) continue;
collectInterceptingPages(
path.join(currentDir, entry.name),
interceptRoot,
convention,
interceptSegment,
routeDir,
appDir,
results,
);
}
}
/**
* Compute the target URL pattern for an intercepting route.
*
* - (.) same level: resolve relative to routeDir
* - (..) one level up: resolve relative to parent of routeDir
* - (..)(..)" two levels up: resolve relative to grandparent of routeDir
* - (...) root: resolve from appDir
*/
function computeInterceptTarget(
convention: string,
interceptSegment: string,
currentDir: string,
interceptRoot: string,
routeDir: string,
appDir: string,
): { pattern: string; params: string[] } | null {
// Determine the base directory for target resolution
let baseDir: string;
switch (convention) {
case ".":
baseDir = routeDir;
break;
case "..":
baseDir = path.dirname(routeDir);
break;
case "../..":
baseDir = path.dirname(path.dirname(routeDir));
break;
case "...":
baseDir = appDir;
break;
default:
return null;
}
// Build the target URL segments from baseDir relative to appDir
const baseParts = path
.relative(appDir, baseDir)
.split(path.sep)
.filter(Boolean);
// Add the intercept segment and any nested path segments
const nestedParts = path
.relative(interceptRoot, currentDir)
.split(path.sep)
.filter(Boolean);
const allSegments = [...baseParts, interceptSegment, ...nestedParts];
// Convert segments to URL pattern
const urlSegments: string[] = [];
const params: string[] = [];
for (const segment of allSegments) {
if (segment === ".") continue;
// Route groups and @ slots are transparent
if (segment.startsWith("(") && segment.endsWith(")")) continue;
if (segment.startsWith("@")) continue;
// Dynamic segments
const catchAllMatch = segment.match(/^\[\.\.\.([\w-]+)\]$/);
if (catchAllMatch) {
params.push(catchAllMatch[1]);
urlSegments.push(`:${catchAllMatch[1]}+`);
continue;
}
const optionalCatchAllMatch = segment.match(/^\[\[\.\.\.([\w-]+)\]\]$/);
if (optionalCatchAllMatch) {
params.push(optionalCatchAllMatch[1]);
urlSegments.push(`:${optionalCatchAllMatch[1]}*`);
continue;
}
const dynamicMatch = segment.match(/^\[([\w-]+)\]$/);
if (dynamicMatch) {
params.push(dynamicMatch[1]);
urlSegments.push(`:${dynamicMatch[1]}`);
continue;
}
// Decode URL-encoded directory names (e.g., %5Fsites -> _sites)
try {
urlSegments.push(decodeURIComponent(segment));
} catch {
urlSegments.push(segment);
}
}
const pattern = "/" + urlSegments.join("/");
return { pattern: pattern === "/" ? "/" : pattern, params };
}
/**
* Find a file by name (without extension) in a directory.
* Checks .tsx, .ts, .jsx, .js extensions.
*/
function findFile(dir: string, name: string): string | null {
const extensions = [".tsx", ".ts", ".jsx", ".js"];
for (const ext of extensions) {
const filePath = path.join(dir, name + ext);
if (fs.existsSync(filePath)) return filePath;
}
return null;
}
/**
* Match a URL against App Router routes.
*/
export function matchAppRoute(
url: string,
routes: AppRoute[],
): { route: AppRoute; params: Record<string, string | string[]> } | null {
const pathname = url.split("?")[0];
let normalizedUrl = pathname === "/" ? "/" : pathname.replace(/\/$/, "");
try {
normalizedUrl = decodeURIComponent(normalizedUrl);
} catch {
/* malformed percent-encoding — match as-is */
}
for (const route of routes) {
const params = matchPattern(normalizedUrl, route.pattern);
if (params !== null) {
return { route, params };
}
}
return null;
}
function matchPattern(
url: string,
pattern: string,
): Record<string, string | string[]> | null {
const urlParts = url.split("/").filter(Boolean);
const patternParts = pattern.split("/").filter(Boolean);
const params: Record<string, string | string[]> = Object.create(null);
for (let i = 0; i < patternParts.length; i++) {
const pp = patternParts[i];
if (pp.endsWith("+")) {
const paramName = pp.slice(1, -1);
const remaining = urlParts.slice(i);
if (remaining.length === 0) return null;
params[paramName] = remaining;
return params;
}
if (pp.endsWith("*")) {
const paramName = pp.slice(1, -1);
const remaining = urlParts.slice(i);
params[paramName] = remaining;
return params;
}
if (pp.startsWith(":")) {
const paramName = pp.slice(1);
if (i >= urlParts.length) return null;
params[paramName] = urlParts[i];
continue;
}
if (i >= urlParts.length || urlParts[i] !== pp) return null;
}
if (urlParts.length !== patternParts.length) return null;
return params;
}
/**
* Route precedence — lower score is higher priority.
* Matches Next.js specificity rules:
* 1. Static routes first (scored by segment count, more = more specific)
* 2. Dynamic segments penalized by position
* 3. Catch-all comes after dynamic
* 4. Optional catch-all last
* 5. Lexicographic tiebreaker for determinism
*
* Key insight: routes with static prefix segments should have higher priority
* than catch-all routes without them. E.g., /_sites/:subdomain/:slug* should
* match before /:slug* because "_sites" must match exactly.
*/
function routePrecedence(pattern: string): number {
const parts = pattern.split("/").filter(Boolean);
let score = 0;
let staticPrefixCount = 0;
// Count static prefix segments (before first dynamic/catch-all)
for (const p of parts) {
if (p.startsWith(":") || p.endsWith("+") || p.endsWith("*")) break;
staticPrefixCount++;
}
// Static prefix segments dramatically reduce score (increase priority).
// Each static prefix segment gives -10000 priority boost.
score -= staticPrefixCount * 10000;
for (let i = 0; i < parts.length; i++) {
const p = parts[i];
if (p.endsWith("+")) {
score += 1000 + i; // catch-all: moderate penalty
} else if (p.endsWith("*")) {
score += 2000 + i; // optional catch-all: high penalty
} else if (p.startsWith(":")) {
score += 100 + i; // dynamic: small penalty by position
}
// static segments after first dynamic don't contribute extra
}
return score;
}