feat(fs): raise preview size cap for PDFs and images (#1096)

Local IPC bumps to 50MB; SSH relay bumps to 10MB (bounded by the 16MB JSON-RPC frame cap). Text and search paths keep the 5MB cap.

src/main/ipc/filesystem.ts

@@ -45,6 +45,14 @@ import { getSshFilesystemProvider } from '../providers/ssh-filesystem-dispatch'
 import { getSshGitProvider } from '../providers/ssh-git-dispatch'
 
 const MAX_FILE_SIZE = 5 * 1024 * 1024 // 5MB
+// Why: previewable binaries (PDFs, images) are rendered by the viewer as
+// base64 blobs, not parsed as text — 5MB is tight for real-world PDFs, and
+// raising this cap only affects binary preview, not text/search paths.
+// The relay (SSH) uses a smaller 10MB cap because its JSON-RPC frames are
+// bounded by MAX_MESSAGE_SIZE = 16MB; the local IPC path has no such limit,
+// so 50MB covers real-world PDFs (specs, datasheets, image-heavy contracts).
+// See src/relay/fs-handler-utils.ts for the remote-side reasoning.
+const MAX_PREVIEWABLE_BINARY_SIZE = 50 * 1024 * 1024 // 50MB
 const DEFAULT_SEARCH_MAX_RESULTS = 2000
 const MAX_MATCHES_PER_FILE = 100
 const SEARCH_TIMEOUT_MS = 15000
@@ -124,14 +132,15 @@ export function registerFilesystemHandlers(store: Store): void {
       }
       const filePath = await resolveAuthorizedPath(args.filePath, store)
       const stats = await stat(filePath)
-      if (stats.size > MAX_FILE_SIZE) {
+      const mimeType = PREVIEWABLE_BINARY_MIME_TYPES[extname(filePath).toLowerCase()]
+      const sizeLimit = mimeType ? MAX_PREVIEWABLE_BINARY_SIZE : MAX_FILE_SIZE
+      if (stats.size > sizeLimit) {
         throw new Error(
-          `File too large: ${(stats.size / 1024 / 1024).toFixed(1)}MB exceeds ${MAX_FILE_SIZE / 1024 / 1024}MB limit`
+          `File too large: ${(stats.size / 1024 / 1024).toFixed(1)}MB exceeds ${sizeLimit / 1024 / 1024}MB limit`
         )
       }
 
       const buffer = await readFile(filePath)
-      const mimeType = PREVIEWABLE_BINARY_MIME_TYPES[extname(filePath).toLowerCase()]
       if (mimeType) {
         return {
           content: buffer.toString('base64'),

src/relay/fs-handler-utils.ts

@@ -11,6 +11,20 @@ import { execFile, type ChildProcess } from 'child_process'
 // ─── Constants ───────────────────────────────────────────────────────
 
 export const MAX_FILE_SIZE = 5 * 1024 * 1024
+// Why: previewable binaries (PDFs, images) are rendered by the viewer as
+// base64 blobs, not parsed as text — 5MB is tight for real-world PDFs, and
+// raising this cap only affects binary preview, not text/search paths.
+// Why 10MB (not 50MB like the local main-process cap): the SSH relay ships
+// every JSON-RPC response in a single framed message capped at
+// MAX_MESSAGE_SIZE = 16MB (see src/relay/protocol.ts and
+// src/main/ssh/relay-protocol.ts). A file here is sent as base64 inside JSON,
+// so 10MB on disk → ~13.3MB base64 → ~13.4MB framed payload, leaving headroom
+// under the 16MB frame cap. Raising this cap without first landing streaming
+// reads would cause the encoder to throw "Message too large" and the decoder
+// to discard oversized frames for borderline files. The proper path to a
+// higher remote cap is streaming fs.readFile over the relay, not bumping
+// MAX_MESSAGE_SIZE (which would introduce head-of-line blocking on the mux).
+export const MAX_PREVIEWABLE_BINARY_SIZE = 10 * 1024 * 1024
 export const SEARCH_TIMEOUT_MS = 15_000
 export const MAX_MATCHES_PER_FILE = 100
 export const DEFAULT_MAX_RESULTS = 2000

src/relay/fs-handler.ts

@@ -17,6 +17,7 @@ import type { RelayContext } from './context'
 import { expandTilde } from './context'
 import {
   MAX_FILE_SIZE,
+  MAX_PREVIEWABLE_BINARY_SIZE,
   DEFAULT_MAX_RESULTS,
   IMAGE_MIME_TYPES,
   isBinaryBuffer,
@@ -82,14 +83,15 @@ export class FsHandler {
     const filePath = expandTilde(params.filePath as string)
     await this.context.validatePathResolved(filePath)
     const stats = await stat(filePath)
-    if (stats.size > MAX_FILE_SIZE) {
+    const mimeType = IMAGE_MIME_TYPES[extname(filePath).toLowerCase()]
+    const sizeLimit = mimeType ? MAX_PREVIEWABLE_BINARY_SIZE : MAX_FILE_SIZE
+    if (stats.size > sizeLimit) {
       throw new Error(
-        `File too large: ${(stats.size / 1024 / 1024).toFixed(1)}MB exceeds ${MAX_FILE_SIZE / 1024 / 1024}MB limit`
+        `File too large: ${(stats.size / 1024 / 1024).toFixed(1)}MB exceeds ${sizeLimit / 1024 / 1024}MB limit`
       )
     }
 
     const buffer = await readFile(filePath)
-    const mimeType = IMAGE_MIME_TYPES[extname(filePath).toLowerCase()]
     if (mimeType) {
       return { content: buffer.toString('base64'), isBinary: true, isImage: true, mimeType }
     }