Retry texlab with full text on state loss and clamp offsets

Author: Makiras

services/web/app/src/Features/Texlab/TexlabController.mjs

@@ -1,5 +1,5 @@
 import SessionManager from '../Authentication/SessionManager.mjs'
-import TexlabManager from './TexlabManager.mjs'
+import TexlabManager, { REQUIRE_FULL_TEXT } from './TexlabManager.mjs'
 import texlabLogger from './TexlabLogger.mjs'
 
 async function complete(req, res) {
@@ -29,6 +29,9 @@ async function complete(req, res) {
     })
     res.json({ items: result.items || [] })
   } catch (err) {
+    if (err && err.code === REQUIRE_FULL_TEXT) {
+      return res.status(409).json({ requiresFullText: true })
+    }
     texlabLogger.error({ err, userId, projectId }, '[Texlab] completion failed')
     res.status(500).json({ error: 'texlab completion failed' })
   }

services/web/app/src/Features/Texlab/TexlabManager.mjs

@@ -37,6 +37,8 @@ const requestBlobAsync = (projectId, fileHash) =>
     })
   })
 
+export const REQUIRE_FULL_TEXT = 'REQUIRES_FULL_TEXT'
+
 function buildHeaders(payload) {
   return `Content-Length: ${Buffer.byteLength(payload, 'utf8')}\r\n\r\n`
 }
@@ -394,6 +396,11 @@ class TexlabProcess {
     let textForPosition = fullText ?? currentText
 
     if (!existing) {
+      if (typeof fullText !== 'string') {
+        const err = new Error(REQUIRE_FULL_TEXT)
+        err.code = REQUIRE_FULL_TEXT
+        throw err
+      }
       const initialText = fullText ?? ''
       this.docs.set(uri, { version: desiredVersion, text: initialText })
       textForPosition = initialText
@@ -438,7 +445,19 @@ class TexlabProcess {
       }
     }
 
-    const position = positionFromOffset(textForPosition || '', offset)
+    const baseText = textForPosition || ''
+    let safeOffset = offset
+    if (safeOffset > baseText.length) {
+      safeOffset = baseText.length
+      texlabLogger.warn(
+        { offset, safeOffset, length: baseText.length },
+        '[Texlab] clamped completion offset'
+      )
+    } else if (safeOffset < 0) {
+      safeOffset = 0
+    }
+
+    const position = positionFromOffset(baseText, safeOffset)
     return await this.sendRequest(
       {
         jsonrpc: '2.0',

services/web/modules/texlab-completion/frontend/texlab-completion-source.ts

@@ -1,6 +1,6 @@
 import { CompletionContext, CompletionResult } from '@codemirror/autocomplete'
 import getMeta from '@/utils/meta'
-import { postJSON } from '@/infrastructure/fetch-json'
+import { FetchError, postJSON } from '@/infrastructure/fetch-json'
 
 type DocCache = {
   text: string
@@ -78,16 +78,37 @@ async function fetchTexlabCompletion(
     }
   }
 
-  try {
-    const res = await postJSON(`/project/${projectId}/texlab/complete`, {
-      body: {
-        docPath,
-        offset,
-        version,
-        fullText,
-        changes,
-      },
+  async function sendRequest(forceFullText = false) {
+    const payloadVersion =
+      forceFullText && cached ? cached.version + 1 : version
+    const payloadText = forceFullText ? cached?.text ?? docText : fullText
+    const payload = {
+      docPath,
+      offset,
+      version: payloadVersion,
+      fullText: payloadText,
+      changes: forceFullText ? undefined : changes,
+    }
+    if (payloadText) {
+      docCache.set(docPath, { text: payloadText, version: payloadVersion })
+    }
+    return await postJSON(`/project/${projectId}/texlab/complete`, {
+      body: payload,
     })
+  }
+
+  try {
+    let res: any
+    try {
+      res = await sendRequest(false)
+    } catch (err) {
+      if (err instanceof FetchError && err.response?.status === 409) {
+        // Server lost state, retry with full text
+        res = await sendRequest(true)
+      } else {
+        throw err
+      }
+    }
     const items = (res.items || []).map((item: any) => {
       const label = item.label || item.insertText || ''
       const insertText = item.insertText || label