diff --git a/tests/tools/curation/dedupeByProximity.test.ts b/tests/tools/curation/dedupeByProximity.test.ts
index d257a600a..6eebc4cce 100644
--- a/tests/tools/curation/dedupeByProximity.test.ts
+++ b/tests/tools/curation/dedupeByProximity.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from 'vitest';
 
-import { dedupeByProximity, type ProximityPoint } from '../../../tools/curation/dedupeByProximity.js';
-import type { Vec3 } from '../../../src/@types/math/Vec3.js';
+import { dedupeByProximity, type ProximityPoint } from '../../../tools/curation/dedupeByProximity';
+import type { Vec3 } from '../../../src/@types/math/Vec3';
 
 describe('dedupeByProximity', () => {
   it('drops a candidate inside a featured anchor radius', () => {
diff --git a/tests/tools/curation/writeMetaSidecar.test.ts b/tests/tools/curation/writeMetaSidecar.test.ts
index d489ab666..7b3657a88 100644
--- a/tests/tools/curation/writeMetaSidecar.test.ts
+++ b/tests/tools/curation/writeMetaSidecar.test.ts
@@ -4,7 +4,7 @@ import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { randomBytes } from 'node:crypto';
 
-import { writeMetaSidecar, type MetaSidecarEntry } from '../../../tools/curation/writeMetaSidecar.js';
+import { writeMetaSidecar, type MetaSidecarEntry } from '../../../tools/curation/writeMetaSidecar';
 
 function tmpPath(): string {
   return join(tmpdir(), `writeMetaSidecar-${randomBytes(6).toString('hex')}.json`);
diff --git a/tests/tools/famous-curator/cropExtract.test.ts b/tests/tools/famous-curator/cropExtract.test.ts
index 5c66840da..5ea452e45 100644
--- a/tests/tools/famous-curator/cropExtract.test.ts
+++ b/tests/tools/famous-curator/cropExtract.test.ts
@@ -8,7 +8,7 @@
  */
 import { describe, it, expect } from 'vitest';
 import sharp from 'sharp';
-import { rotatedExtract } from '../../../tools/famous-curator/plugin/cropExtract.js';
+import { rotatedExtract } from '../../../tools/famous-curator/plugin/cropExtract';
 import { mkdtempSync, writeFileSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
diff --git a/tests/tools/famous-curator/routes/process.deproject.test.ts b/tests/tools/famous-curator/routes/process.deproject.test.ts
index 03565e9fe..159a4d865 100644
--- a/tests/tools/famous-curator/routes/process.deproject.test.ts
+++ b/tests/tools/famous-curator/routes/process.deproject.test.ts
@@ -17,7 +17,7 @@ import { mkdtempSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import sharp from 'sharp';
-import { handleProcess } from '../../../../tools/famous-curator/plugin/routes/process.js';
+import { handleProcess } from '../../../../tools/famous-curator/plugin/routes/process';
 import type { RecipeDisk } from '../../../../tools/famous-curator/plugin/recipe';
 
 async function seedSession(prefix: string): Promise<{ tmpId: string; dir: string }> {
diff --git a/tests/tools/famous-curator/routes/process.test.ts b/tests/tools/famous-curator/routes/process.test.ts
index b15c79f7b..56832011b 100644
--- a/tests/tools/famous-curator/routes/process.test.ts
+++ b/tests/tools/famous-curator/routes/process.test.ts
@@ -11,7 +11,7 @@ import { existsSync, mkdirSync, mkdtempSync, writeFileSync, readFileSync } from
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import sharp from 'sharp';
-import { handleProcess } from '../../../../tools/famous-curator/plugin/routes/process.js';
+import { handleProcess } from '../../../../tools/famous-curator/plugin/routes/process';
 
 async function seedSession(): Promise<{ tmpId: string; dir: string }> {
   // 128×128 PNG with a bright disc in the middle so alpha-pass output
diff --git a/tools/catalog/buildAllBins.ts b/tools/catalog/buildAllBins.ts
index 9564afba5..af310c494 100644
--- a/tools/catalog/buildAllBins.ts
+++ b/tools/catalog/buildAllBins.ts
@@ -34,39 +34,39 @@ import { createInterface } from 'node:readline';
 import { fileURLToPath } from 'node:url';
 import type { SourceType } from '../../src/@types/data/SourceType';
 
-import { parseSdssCsv } from '../parsers/sdssCsv.js';
-import { parseTwoMrs, parseXscShapeCsv } from '../parsers/twoMrs.js';
-import type { XscShapeMap } from '../parsers/twoMrs.js';
-import { parseGladeLine, parseGlade2masxPgcLine, parseHyperLedaCsv } from '../parsers/glade.js';
-import type { HyperLedaShapeMap } from '../parsers/glade.js';
-import { parseMilliquas } from '../parsers/milliquas.js';
-import type { MilliquasParseResult } from '../parsers/milliquas.js';
-import type { ParsedRecord } from '../parsers/common.js';
-import { crossMatch } from './crossMatch.js';
-import { dropFamousMatches } from './dropFamousMatches.js';
-import type { FamousSkyPosition } from './dropFamousMatches.js';
-import { parseFamousSeed } from '../parsers/famousSeed.js';
-
-import { encodeGalaxyCatalog } from '../../src/data/galaxyCatalogFormat.js';
-import { raDecZToCartesian } from '../../src/utils/math/index.js';
-import { raDecDistToCartesian } from '../../src/utils/math/raDecDistToCartesian.js';
-import { fallbackOrientation } from '../../src/utils/random/fallbackOrientation.js';
-import { catalogDistanceFor } from './catalogDistanceFor.js';
-import { CUTOFF_MPC } from './localVolumeCutoff.js';
-import type { Cf4CatalogIndex } from '../parsers/cosmicflows4.js';
-import { loadCf4CatalogIndex } from '../parsers/cosmicflows4.js';
-import { DEFAULT_GALAXY_DIAMETER_KPC } from '../../src/utils/math/galaxyDiameterKpc.js';
-import { Source, SOURCE_REGISTRY } from '../../src/data/sources.js';
-import type { GalaxyCatalog } from '../../src/@types/data/GalaxyCatalog.js';
-import { tierTarget, tierFilenameForSource } from '../../src/data/tierTargets.js';
-import type { Tier } from '../../src/@types/data/Tier.js';
-import { subsampleByAbsMag } from './subsampleByAbsMag.js';
-import { rawDataPath } from '../utils/io/rawDataRegistry.js';
+import { parseSdssCsv } from '../parsers/sdssCsv';
+import { parseTwoMrs, parseXscShapeCsv } from '../parsers/twoMrs';
+import type { XscShapeMap } from '../parsers/twoMrs';
+import { parseGladeLine, parseGlade2masxPgcLine, parseHyperLedaCsv } from '../parsers/glade';
+import type { HyperLedaShapeMap } from '../parsers/glade';
+import { parseMilliquas } from '../parsers/milliquas';
+import type { MilliquasParseResult } from '../parsers/milliquas';
+import type { ParsedRecord } from '../parsers/common';
+import { crossMatch } from './crossMatch';
+import { dropFamousMatches } from './dropFamousMatches';
+import type { FamousSkyPosition } from './dropFamousMatches';
+import { parseFamousSeed } from '../parsers/famousSeed';
+
+import { encodeGalaxyCatalog } from '../../src/data/galaxyCatalogFormat';
+import { raDecZToCartesian } from '../../src/utils/math/index';
+import { raDecDistToCartesian } from '../../src/utils/math/raDecDistToCartesian';
+import { fallbackOrientation } from '../../src/utils/random/fallbackOrientation';
+import { catalogDistanceFor } from './catalogDistanceFor';
+import { CUTOFF_MPC } from './localVolumeCutoff';
+import type { Cf4CatalogIndex } from '../parsers/cosmicflows4';
+import { loadCf4CatalogIndex } from '../parsers/cosmicflows4';
+import { DEFAULT_GALAXY_DIAMETER_KPC } from '../../src/utils/math/galaxyDiameterKpc';
+import { Source, SOURCE_REGISTRY } from '../../src/data/sources';
+import type { GalaxyCatalog } from '../../src/@types/data/GalaxyCatalog';
+import { tierTarget, tierFilenameForSource } from '../../src/data/tierTargets';
+import type { Tier } from '../../src/@types/data/Tier';
+import { subsampleByAbsMag } from './subsampleByAbsMag';
+import { rawDataPath } from '../utils/io/rawDataRegistry';
 
 // Re-export so `tests/crossMatch.test.ts` and any other consumer can keep
 // using the documented `tools/buildAllBins` import path.
-export { crossMatch } from './crossMatch.js';
-export type { CrossMatchInputs } from './crossMatch.js';
+export { crossMatch } from './crossMatch';
+export type { CrossMatchInputs } from './crossMatch';
 
 // ─── GalaxyCatalog assembly + write ──────────────────────────────────────────
 
diff --git a/tools/catalog/crossMatch.ts b/tools/catalog/crossMatch.ts
index d458042f1..33414a969 100644
--- a/tools/catalog/crossMatch.ts
+++ b/tools/catalog/crossMatch.ts
@@ -26,7 +26,7 @@
  *   GLADE itself uses to pre-merge its constituent catalogues.
  */
 
-import type { ParsedRecord } from '../parsers/common.js';
+import type { ParsedRecord } from '../parsers/common';
 
 /**
  * Position tolerance: 5 arcseconds expressed in degrees.
diff --git a/tools/catalog/subsampleByAbsMag.ts b/tools/catalog/subsampleByAbsMag.ts
index be32b4582..cf3fb7f54 100644
--- a/tools/catalog/subsampleByAbsMag.ts
+++ b/tools/catalog/subsampleByAbsMag.ts
@@ -38,9 +38,9 @@
  *                non-positive z are dropped regardless of target.
  */
 
-import { absoluteMagnitude } from '../../src/utils/math/absoluteMagnitude.js';
-import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc.js';
-import type { ParsedRecord } from '../parsers/common.js';
+import { absoluteMagnitude } from '../../src/utils/math/absoluteMagnitude';
+import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc';
+import type { ParsedRecord } from '../parsers/common';
 
 export function subsampleByAbsMag(records: ParsedRecord[], target: number): ParsedRecord[] {
   const kept = subsampleIndicesByAbsMag(records, target);
diff --git a/tools/clusters/buildClusters.ts b/tools/clusters/buildClusters.ts
index 138b6ed80..72c73467f 100644
--- a/tools/clusters/buildClusters.ts
+++ b/tools/clusters/buildClusters.ts
@@ -37,19 +37,19 @@ import { readFileSync, writeFileSync } from 'node:fs';
 import { resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 
-import { parseMcxc, type McxcRow } from '../parsers/parseMcxc.js';
-import { parseMscc, type MsccRow } from '../parsers/parseMscc.js';
-import { parseClusterSeed, type ClusterSeedEntry } from '../parsers/parseClusterSeed.js';
-import { encodeClusterCatalog } from '../../src/data/clusterCatalogFormat.js';
-import { rawDataPath } from '../utils/io/rawDataRegistry.js';
-import { writeMetaSidecar } from '../curation/writeMetaSidecar.js';
-import { dedupeByProximity } from '../curation/dedupeByProximity.js';
-import { raDecDistToEqCart } from '../../src/utils/math/raDecDistToEqCart.js';
-import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc.js';
-import { H0_KM_S_MPC } from '../../src/utils/math/constants.js';
-import type { ClusterCatalog } from '../../src/@types/data/ClusterCatalog.js';
-import type { ClusterCategoryByte } from '../../src/@types/data/ClusterCatalog.js';
-import type { Vec3 } from '../../src/@types/math/Vec3.js';
+import { parseMcxc, type McxcRow } from '../parsers/parseMcxc';
+import { parseMscc, type MsccRow } from '../parsers/parseMscc';
+import { parseClusterSeed, type ClusterSeedEntry } from '../parsers/parseClusterSeed';
+import { encodeClusterCatalog } from '../../src/data/clusterCatalogFormat';
+import { rawDataPath } from '../utils/io/rawDataRegistry';
+import { writeMetaSidecar } from '../curation/writeMetaSidecar';
+import { dedupeByProximity } from '../curation/dedupeByProximity';
+import { raDecDistToEqCart } from '../../src/utils/math/raDecDistToEqCart';
+import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc';
+import { H0_KM_S_MPC } from '../../src/utils/math/constants';
+import type { ClusterCatalog } from '../../src/@types/data/ClusterCatalog';
+import type { ClusterCategoryByte } from '../../src/@types/data/ClusterCatalog';
+import type { Vec3 } from '../../src/@types/math/Vec3';
 
 // ── Tunable threshold constants ───────────────────────────────────────────────
 //
diff --git a/tools/curation/dedupeByProximity.ts b/tools/curation/dedupeByProximity.ts
index 8f77e4b8a..2e20e4c31 100644
--- a/tools/curation/dedupeByProximity.ts
+++ b/tools/curation/dedupeByProximity.ts
@@ -21,7 +21,7 @@
  * pair.  Pure function; preserves input order of surviving candidates.
  */
 
-import type { Vec3 } from '../../src/@types/math/Vec3.js';
+import type { Vec3 } from '../../src/@types/math/Vec3';
 
 export type ProximityPoint = { worldPos: Vec3 };
 
diff --git a/tools/famous-curator/plugin/paths.ts b/tools/famous-curator/plugin/paths.ts
index 31890d2c5..4ebefbc94 100644
--- a/tools/famous-curator/plugin/paths.ts
+++ b/tools/famous-curator/plugin/paths.ts
@@ -18,7 +18,7 @@
  */
 import { resolve } from 'node:path';
 
-import { RAW_DATA } from '../../utils/io/rawDataRegistry.js';
+import { RAW_DATA } from '../../utils/io/rawDataRegistry';
 
 export function curatedDir(repoRoot: string): string {
   return resolve(repoRoot, 'public/images/famous-curated');
diff --git a/tools/famous-curator/plugin/routes/export.ts b/tools/famous-curator/plugin/routes/export.ts
index 4eb68cc32..53388e58e 100644
--- a/tools/famous-curator/plugin/routes/export.ts
+++ b/tools/famous-curator/plugin/routes/export.ts
@@ -31,15 +31,15 @@
 import sharp from 'sharp';
 import { existsSync, mkdirSync, rmSync, renameSync, writeFileSync } from 'node:fs';
 import { resolve } from 'node:path';
-import { curatedGalaxyDir, curatedTmpDir, overrideIndexPath } from '../paths.js';
-import { sessionPath } from '../tmpSession.js';
-import { serialiseRecipe, validateRecipeDisk, type Recipe, type RecipeDisk } from '../recipe.js';
-import { upsertOverrideEntry, type OverrideIndex } from '../overrideIndex.js';
-import { applyLuminanceAsAlpha } from '../../../utils/image/applyLuminanceAsAlpha.js';
-import { willDeproject } from '../../../famous/deprojectDisk.js';
-import { squareDeprojectCrop } from '../../../famous/squareDeprojectCrop.js';
-import { deriveFamousCalibration } from '../../../famous/deriveFamousCalibration.js';
-import { publishFamousRuntimeImages } from '../../../famous/publishFamousRuntimeImages.js';
+import { curatedGalaxyDir, curatedTmpDir, overrideIndexPath } from '../paths';
+import { sessionPath } from '../tmpSession';
+import { serialiseRecipe, validateRecipeDisk, type Recipe, type RecipeDisk } from '../recipe';
+import { upsertOverrideEntry, type OverrideIndex } from '../overrideIndex';
+import { applyLuminanceAsAlpha } from '../../../utils/image/applyLuminanceAsAlpha';
+import { willDeproject } from '../../../famous/deprojectDisk';
+import { squareDeprojectCrop } from '../../../famous/squareDeprojectCrop';
+import { deriveFamousCalibration } from '../../../famous/deriveFamousCalibration';
+import { publishFamousRuntimeImages } from '../../../famous/publishFamousRuntimeImages';
 import type { FamousCalibration } from '../../../../src/@types/loading/FamousCalibration';
 
 const FULL_PX = 1024;
diff --git a/tools/famous-curator/plugin/routes/galaxies.ts b/tools/famous-curator/plugin/routes/galaxies.ts
index 85c12210f..08c7dce44 100644
--- a/tools/famous-curator/plugin/routes/galaxies.ts
+++ b/tools/famous-curator/plugin/routes/galaxies.ts
@@ -8,11 +8,11 @@
  */
 import { readFileSync, existsSync } from 'node:fs';
 import { resolve } from 'node:path';
-import { parseFamousSeed } from '../../../parsers/famousSeed.js';
-import { RAW_DATA } from '../../../utils/io/rawDataRegistry.js';
-import { loadOverrideIndex } from '../overrideIndex.js';
-import { overrideIndexPath, recipePath } from '../paths.js';
-import { parseRecipe } from '../recipe.js';
+import { parseFamousSeed } from '../../../parsers/famousSeed';
+import { RAW_DATA } from '../../../utils/io/rawDataRegistry';
+import { loadOverrideIndex } from '../overrideIndex';
+import { overrideIndexPath, recipePath } from '../paths';
+import { parseRecipe } from '../recipe';
 
 export type GalaxyListEntry = {
   id: string;
diff --git a/tools/famous-curator/plugin/routes/process.ts b/tools/famous-curator/plugin/routes/process.ts
index cafef36b4..852f2e6b3 100644
--- a/tools/famous-curator/plugin/routes/process.ts
+++ b/tools/famous-curator/plugin/routes/process.ts
@@ -17,13 +17,13 @@
 import sharp from 'sharp';
 import { writeFileSync } from 'node:fs';
 import { resolve } from 'node:path';
-import { sessionPath } from '../tmpSession.js';
-import { runStarnet, type StarnetConfig } from '../starnet.js';
-import { applyLuminanceAsAlpha } from '../../../utils/image/applyLuminanceAsAlpha.js';
-import { rotatedExtract } from '../cropExtract.js';
-import { deprojectDisk, willDeproject } from '../../../famous/deprojectDisk.js';
-import { squareDeprojectCrop } from '../../../famous/squareDeprojectCrop.js';
-import { validateRecipeDisk, type RecipeDisk } from '../recipe.js';
+import { sessionPath } from '../tmpSession';
+import { runStarnet, type StarnetConfig } from '../starnet';
+import { applyLuminanceAsAlpha } from '../../../utils/image/applyLuminanceAsAlpha';
+import { rotatedExtract } from '../cropExtract';
+import { deprojectDisk, willDeproject } from '../../../famous/deprojectDisk';
+import { squareDeprojectCrop } from '../../../famous/squareDeprojectCrop';
+import { validateRecipeDisk, type RecipeDisk } from '../recipe';
 
 const PREVIEW_PX = 512;
 
diff --git a/tools/famous-curator/plugin/routes/processAlphaOnly.ts b/tools/famous-curator/plugin/routes/processAlphaOnly.ts
index 642adae22..9ee3c192e 100644
--- a/tools/famous-curator/plugin/routes/processAlphaOnly.ts
+++ b/tools/famous-curator/plugin/routes/processAlphaOnly.ts
@@ -12,8 +12,8 @@
 import sharp from 'sharp';
 import { existsSync, writeFileSync } from 'node:fs';
 import { resolve } from 'node:path';
-import { sessionPath } from '../tmpSession.js';
-import { applyLuminanceAsAlpha } from '../../../utils/image/applyLuminanceAsAlpha.js';
+import { sessionPath } from '../tmpSession';
+import { applyLuminanceAsAlpha } from '../../../utils/image/applyLuminanceAsAlpha';
 
 const PREVIEW_PX = 512;
 
diff --git a/tools/famous-curator/plugin/routes/resolve.ts b/tools/famous-curator/plugin/routes/resolve.ts
index 051fea72c..50414d1ba 100644
--- a/tools/famous-curator/plugin/routes/resolve.ts
+++ b/tools/famous-curator/plugin/routes/resolve.ts
@@ -22,7 +22,7 @@
  * in; tests inject stubs.  Only the `ResolvedMedia` shape is shared,
  * and it crosses as a type-only import — no value-level coupling.
  */
-import type { ResolvedMedia } from '../noirlabResolver.js';
+import type { ResolvedMedia } from '../noirlabResolver';
 
 export type ResolverFn = (html: string, pageUrl: string) => ResolvedMedia | null;
 export type HtmlFetcher = (url: string) => Promise<string>;
diff --git a/tools/famous/buildFamous.ts b/tools/famous/buildFamous.ts
index 34d8ed8d6..5fdd38015 100644
--- a/tools/famous/buildFamous.ts
+++ b/tools/famous/buildFamous.ts
@@ -23,19 +23,19 @@ import { existsSync, readFileSync, writeFileSync } from 'node:fs';
 import { resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 
-import { parseFamousSeed, type FamousEntry } from '../parsers/famousSeed.js';
-import { encodeGalaxyCatalog } from '../../src/data/galaxyCatalogFormat.js';
-import { Source } from '../../src/data/sources.js';
-import { fallbackOrientation } from '../../src/utils/random/fallbackOrientation.js';
-import type { GalaxyCatalog } from '../../src/@types/data/GalaxyCatalog.js';
-import type { FamousMetaEntry } from '../../src/@types/loading/FamousMetaEntry.js';
-import { rawDataPath } from '../utils/io/rawDataRegistry.js';
-import { parseRecipe, type Recipe } from '../famous-curator/plugin/recipe.js';
-import { curatedGalaxyDir } from '../famous-curator/plugin/paths.js';
-import { deriveFamousCalibration } from './deriveFamousCalibration.js';
-import { willDeproject } from './deprojectDisk.js';
-import { squareDeprojectCrop } from './squareDeprojectCrop.js';
-import { writeMetaSidecar } from '../curation/writeMetaSidecar.js';
+import { parseFamousSeed, type FamousEntry } from '../parsers/famousSeed';
+import { encodeGalaxyCatalog } from '../../src/data/galaxyCatalogFormat';
+import { Source } from '../../src/data/sources';
+import { fallbackOrientation } from '../../src/utils/random/fallbackOrientation';
+import type { GalaxyCatalog } from '../../src/@types/data/GalaxyCatalog';
+import type { FamousMetaEntry } from '../../src/@types/loading/FamousMetaEntry';
+import { rawDataPath } from '../utils/io/rawDataRegistry';
+import { parseRecipe, type Recipe } from '../famous-curator/plugin/recipe';
+import { curatedGalaxyDir } from '../famous-curator/plugin/paths';
+import { deriveFamousCalibration } from './deriveFamousCalibration';
+import { willDeproject } from './deprojectDisk';
+import { squareDeprojectCrop } from './squareDeprojectCrop';
+import { writeMetaSidecar } from '../curation/writeMetaSidecar';
 
 /**
  * Convert a curated entry's (RA, Dec, distanceMpc) to Cartesian (x, y, z).
diff --git a/tools/famous/copyHiResToPublic.ts b/tools/famous/copyHiResToPublic.ts
index 13199d9f3..405ac1b99 100644
--- a/tools/famous/copyHiResToPublic.ts
+++ b/tools/famous/copyHiResToPublic.ts
@@ -66,7 +66,7 @@
 import { existsSync, mkdirSync, readdirSync } from 'node:fs';
 import { join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { copyIfChanged, CURATED_DIR, HIRES_RUNTIME_DIR } from './publishFamousRuntimeImages.js';
+import { copyIfChanged, CURATED_DIR, HIRES_RUNTIME_DIR } from './publishFamousRuntimeImages';
 
 type CopyHiResOptions = {
   /** Source root.  Defaults to the curated master dir relative to CWD. */
diff --git a/tools/famous/expandFamousFromCatalogs.ts b/tools/famous/expandFamousFromCatalogs.ts
index acdfa8cde..38e203407 100644
--- a/tools/famous/expandFamousFromCatalogs.ts
+++ b/tools/famous/expandFamousFromCatalogs.ts
@@ -86,18 +86,18 @@
 import { readFileSync, writeFileSync, existsSync, renameSync } from 'node:fs';
 import { resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { rawDataPath } from '../utils/io/rawDataRegistry.js';
+import { rawDataPath } from '../utils/io/rawDataRegistry';
 
-import { parseFamousSeed, validateFamousEntry, type FamousEntry } from '../parsers/famousSeed.js';
+import { parseFamousSeed, validateFamousEntry, type FamousEntry } from '../parsers/famousSeed';
 import {
   parseHyperLedaMeandata,
   hyperLedaMeandataUrl,
   type HyperLedaMeandataRow,
-} from '../parsers/hyperledaMeandata.js';
-import { parseWikipediaSummary, wikipediaSummaryUrl } from '../parsers/wikipediaSummary.js';
-import { loadJsonCache, saveJsonCache } from '../utils/io/jsonCache.js';
-import { parseFlags } from '../utils/cli/args.js';
-import { delay } from '../utils/async/delay.js';
+} from '../parsers/hyperledaMeandata';
+import { parseWikipediaSummary, wikipediaSummaryUrl } from '../parsers/wikipediaSummary';
+import { loadJsonCache, saveJsonCache } from '../utils/io/jsonCache';
+import { parseFlags } from '../utils/cli/args';
+import { delay } from '../utils/async/delay';
 
 // ──────────────────────────────────────────────────────────────────────
 // Constants
diff --git a/tools/famous/fetchFamousImages.ts b/tools/famous/fetchFamousImages.ts
index 53a5d77be..61fc83af6 100644
--- a/tools/famous/fetchFamousImages.ts
+++ b/tools/famous/fetchFamousImages.ts
@@ -105,23 +105,23 @@
 import { copyFileSync, existsSync, mkdirSync, readFileSync, statSync, writeFileSync } from 'node:fs';
 import { resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { loadCuratedOverrides, type CuratedOverrideIndex } from './famousCuratedOverrides.js';
-import { rawDataPath } from '../utils/io/rawDataRegistry.js';
+import { loadCuratedOverrides, type CuratedOverrideIndex } from './famousCuratedOverrides';
+import { rawDataPath } from '../utils/io/rawDataRegistry';
 import sharp from 'sharp';
-import { parseFlags } from '../utils/cli/args.js';
-import { loadJsonCache, saveJsonCache } from '../utils/io/jsonCache.js';
-import { parseFamousSeed, type FamousEntry } from '../parsers/famousSeed.js';
+import { parseFlags } from '../utils/cli/args';
+import { loadJsonCache, saveJsonCache } from '../utils/io/jsonCache';
+import { parseFamousSeed, type FamousEntry } from '../parsers/famousSeed';
 import {
   parseWikipediaSummary,
   wikipediaSummaryUrl,
   type WikipediaSummary,
-} from '../parsers/wikipediaSummary.js';
+} from '../parsers/wikipediaSummary';
 import {
   applyRadialFade,
   applyTransparency,
   sampleCornerColor,
   type RGBA,
-} from './famousImageProcessor.js';
+} from './famousImageProcessor';
 
 // ──────────────────────────────────────────────────────────────────────
 // Constants — Wikipedia path
diff --git a/tools/fetch/fetchClusterCatalogs.ts b/tools/fetch/fetchClusterCatalogs.ts
index 208fb9292..058b95052 100644
--- a/tools/fetch/fetchClusterCatalogs.ts
+++ b/tools/fetch/fetchClusterCatalogs.ts
@@ -16,8 +16,8 @@
 import { readFileSync } from 'node:fs';
 import { fileURLToPath } from 'node:url';
 
-import { downloadWithResume, sha256OfFile } from './fetchCosmicflows4.js';
-import { rawDataPath } from '../utils/io/rawDataRegistry.js';
+import { downloadWithResume, sha256OfFile } from './fetchCosmicflows4';
+import { rawDataPath } from '../utils/io/rawDataRegistry';
 
 // ── CDS FTP URLs ────────────────────────────────────────────────────────────
 
diff --git a/tools/filaments/buildFilaments.ts b/tools/filaments/buildFilaments.ts
index c86abeb11..b39864e5c 100644
--- a/tools/filaments/buildFilaments.ts
+++ b/tools/filaments/buildFilaments.ts
@@ -69,18 +69,18 @@ import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';
 import { resolve, dirname, basename, join } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import type { SourceType } from '../../src/@types/data/SourceType';
-import { rawDataPath } from '../utils/io/rawDataRegistry.js';
+import { rawDataPath } from '../utils/io/rawDataRegistry';
 
-import { decodeGalaxyCatalog } from '../../src/data/galaxyCatalogFormat.js';
-import { parseNDskl, skeletonToFilamentCloud } from '../parsers/ndskl.js';
-import { encodeFilaments } from '../../src/data/filamentBinaryFormat.js';
-import type { GalaxyCatalog } from '../../src/@types/data/GalaxyCatalog.js';
-import { Source } from '../../src/data/sources.js';
-import { surveyFluxLimit } from '../../src/data/surveyFluxLimits.js';
-import { absoluteFromApparent, dMaxFromAbsolute } from '../../src/utils/math/distanceModulus.js';
-import { mulberry32 } from '../../src/utils/random/mulberry32.js';
-import { computeAngularWeights } from '../../src/services/engine/bake/computeAngularWeights.js';
-import { gaussian } from '../utils/random/gaussian.js';
+import { decodeGalaxyCatalog } from '../../src/data/galaxyCatalogFormat';
+import { parseNDskl, skeletonToFilamentCloud } from '../parsers/ndskl';
+import { encodeFilaments } from '../../src/data/filamentBinaryFormat';
+import type { GalaxyCatalog } from '../../src/@types/data/GalaxyCatalog';
+import { Source } from '../../src/data/sources';
+import { surveyFluxLimit } from '../../src/data/surveyFluxLimits';
+import { absoluteFromApparent, dMaxFromAbsolute } from '../../src/utils/math/distanceModulus';
+import { mulberry32 } from '../../src/utils/random/mulberry32';
+import { computeAngularWeights } from '../../src/services/engine/bake/computeAngularWeights';
+import { gaussian } from '../utils/random/gaussian';
 
 /**
  * Default persistence cut in σ.  Lower = more filaments accepted as
diff --git a/tools/parsers/common.ts b/tools/parsers/common.ts
index 0fceb708d..8038c7527 100644
--- a/tools/parsers/common.ts
+++ b/tools/parsers/common.ts
@@ -20,7 +20,7 @@
  * not a distinct absent state requiring extra narrowing.
  */
 
-import { Source } from '../../src/data/sources.js';
+import { Source } from '../../src/data/sources';
 import type { SourceType } from '../../src/@types/data/SourceType';
 
 export type ParsedRecord = {
diff --git a/tools/parsers/glade.ts b/tools/parsers/glade.ts
index fe68e024a..932473c9f 100644
--- a/tools/parsers/glade.ts
+++ b/tools/parsers/glade.ts
@@ -93,14 +93,14 @@
  * objID is always `0n` — see the cross-match note above.
  */
 
-import { Source } from '../../src/data/sources.js';
-import { type ParsedRecord } from './common.js';
+import { Source } from '../../src/data/sources';
+import { type ParsedRecord } from './common';
 import {
   galaxyDiameterKpc,
   DEFAULT_GALAXY_DIAMETER_KPC,
-} from '../../src/utils/math/galaxyDiameterKpc.js';
-import { absoluteMagnitude } from '../../src/utils/math/absoluteMagnitude.js';
-import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc.js';
+} from '../../src/utils/math/galaxyDiameterKpc';
+import { absoluteMagnitude } from '../../src/utils/math/absoluteMagnitude';
+import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc';
 
 /**
  * Map from PGC string (no padding, no leading zeros stripped) to HyperLEDA's
diff --git a/tools/parsers/milliquas.ts b/tools/parsers/milliquas.ts
index b5a812a72..77e61bb71 100644
--- a/tools/parsers/milliquas.ts
+++ b/tools/parsers/milliquas.ts
@@ -31,12 +31,12 @@
  * `MQ J<RA><Dec>` IAU name.
  */
 
-import { Source } from '../../src/data/sources.js';
+import { Source } from '../../src/data/sources';
 import {
   MILLIQUAS_CLASS_BYTE,
   MILLIQUAS_PARENT_SURVEY_BYTE,
-} from '../../src/data/sourceClass.js';
-import { nonCommentLines, type ParsedRecord } from './common.js';
+} from '../../src/data/sourceClass';
+import { nonCommentLines, type ParsedRecord } from './common';
 
 // ─── Byte ranges (1-based inclusive, as published in the upstream ReadMe) ──
 
diff --git a/tools/parsers/parseMcxc.ts b/tools/parsers/parseMcxc.ts
index 140e7ddfe..96da225a8 100644
--- a/tools/parsers/parseMcxc.ts
+++ b/tools/parsers/parseMcxc.ts
@@ -30,7 +30,7 @@
  * producing NaN.
  */
 
-import { nonCommentLines, slot } from './common.js';
+import { nonCommentLines, slot } from './common';
 
 /** Minimum useful line length — R500 column ends at byte 204. */
 const MIN_LINE_LEN = 204;
diff --git a/tools/parsers/parseMscc.ts b/tools/parsers/parseMscc.ts
index 618c113e2..62294362b 100644
--- a/tools/parsers/parseMscc.ts
+++ b/tools/parsers/parseMscc.ts
@@ -68,7 +68,7 @@
  * faithful column reader; it does not interpret units.
  */
 
-import { nonCommentLines, slot } from './common.js';
+import { nonCommentLines, slot } from './common';
 
 /** Minimum useful line length — all required fields end at byte 51. */
 const MIN_LINE_LEN = 51;
diff --git a/tools/parsers/sdssCsv.ts b/tools/parsers/sdssCsv.ts
index 09e5159ad..8abff6eb8 100644
--- a/tools/parsers/sdssCsv.ts
+++ b/tools/parsers/sdssCsv.ts
@@ -32,10 +32,10 @@
  *   them inside the row loop.
  */
 
-import { Source } from '../../src/data/sources.js';
-import { arcsecToKpc } from '../../src/utils/math/arcsecToKpc.js';
-import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc.js';
-import { nonCommentLines, type ParsedRecord } from './common.js';
+import { Source } from '../../src/data/sources';
+import { arcsecToKpc } from '../../src/utils/math/arcsecToKpc';
+import { redshiftToDistanceMpc } from '../../src/utils/math/redshiftToDistanceMpc';
+import { nonCommentLines, type ParsedRecord } from './common';
 
 /**
  * Result of parsing an SDSS CSV: the validated records plus a count of
diff --git a/tools/parsers/twoMrs.ts b/tools/parsers/twoMrs.ts
index f3dee47a4..ddf0e677d 100644
--- a/tools/parsers/twoMrs.ts
+++ b/tools/parsers/twoMrs.ts
@@ -68,9 +68,9 @@
  * definition; the merger uses 0n as the dedup-skip sentinel.
  */
 
-import { Source } from '../../src/data/sources.js';
-import { nonCommentLines, type ParsedRecord } from './common.js';
-import { arcsecToKpc } from '../../src/utils/math/arcsecToKpc.js';
+import { Source } from '../../src/data/sources';
+import { nonCommentLines, type ParsedRecord } from './common';
+import { arcsecToKpc } from '../../src/utils/math/arcsecToKpc';
 
 /**
  * Speed of light in km/s, used to convert heliocentric velocity cz into