fix(windows): better support MSYS/Git Bash path handling

packages/opencode/src/cli/cmd/tui/routes/session/index.tsx

@@ -1570,7 +1570,7 @@ ToolRegistry.register<typeof WriteTool>({
     return (
       <>
         <ToolTitle icon="←" fallback="Preparing write..." when={done}>
-          Wrote {props.input.filePath}
+          Wrote {normalizePath(props.input.filePath ?? "")}
         </ToolTitle>
         <Show when={done}>
           <line_number fg={theme.textMuted} minWidth={3} paddingRight={1}>
@@ -1838,12 +1838,16 @@ ToolRegistry.register<typeof TodoWriteTool>({
   },
 })
 
-function normalizePath(input?: string) {
+function normalizePath(input?: string, maxLength = 50) {
   if (!input) return ""
-  if (path.isAbsolute(input)) {
-    return path.relative(process.cwd(), input) || "."
-  }
-  return input
+  const normalized = Filesystem.toNativePath(input)
+  const relative = path.isAbsolute(normalized) ? Filesystem.safeRelative(process.cwd(), normalized) || "." : normalized
+  if (relative.length <= maxLength) return relative
+  const parts = relative.split(path.sep).filter(Boolean)
+  const last = parts.at(-1)!
+  const rest = parts.slice(0, -1).join(path.sep)
+  if (!rest) return relative
+  return Locale.truncateMiddle(rest, maxLength - last.length - 1) + path.sep + last
 }
 
 function input(input: Record<string, any>, omit?: string[]): string {

packages/opencode/src/tool/edit.ts

@@ -43,7 +43,8 @@ export const EditTool = Tool.define("edit", {
 
     const agent = await Agent.get(ctx.agent)
 
-    const filePath = path.isAbsolute(params.filePath) ? params.filePath : path.join(Instance.directory, params.filePath)
+    const rawPath = Filesystem.toNativePath(params.filePath)
+    const filePath = path.isAbsolute(rawPath) ? rawPath : path.join(Instance.directory, rawPath)
     if (!Filesystem.contains(Instance.directory, filePath)) {
       const parentDir = path.dirname(filePath)
       if (agent.permission.external_directory === "ask") {
@@ -168,7 +169,7 @@ export const EditTool = Tool.define("edit", {
         diff,
         filediff,
       },
-      title: `${path.relative(Instance.worktree, filePath)}`,
+      title: `${Filesystem.safeRelative(Instance.worktree, filePath)}`,
       output,
     }
   },

packages/opencode/src/tool/glob.ts

@@ -4,6 +4,7 @@ import { Tool } from "./tool"
 import DESCRIPTION from "./glob.txt"
 import { Ripgrep } from "../file/ripgrep"
 import { Instance } from "../project/instance"
+import { Filesystem } from "../util/filesystem"
 
 export const GlobTool = Tool.define("glob", {
   description: DESCRIPTION,
@@ -17,8 +18,8 @@ export const GlobTool = Tool.define("glob", {
       ),
   }),
   async execute(params) {
-    let search = params.path ?? Instance.directory
-    search = path.isAbsolute(search) ? search : path.resolve(Instance.directory, search)
+    const rawPath = params.path ? Filesystem.toNativePath(params.path) : Instance.directory
+    const search = path.isAbsolute(rawPath) ? rawPath : path.resolve(Instance.directory, rawPath)
 
     const limit = 100
     const files = []
@@ -54,7 +55,7 @@ export const GlobTool = Tool.define("glob", {
     }
 
     return {
-      title: path.relative(Instance.worktree, search),
+      title: Filesystem.safeRelative(Instance.worktree, search),
       metadata: {
         count: files.length,
         truncated,

packages/opencode/src/tool/grep.ts

@@ -4,6 +4,7 @@ import { Ripgrep } from "../file/ripgrep"
 
 import DESCRIPTION from "./grep.txt"
 import { Instance } from "../project/instance"
+import { Filesystem } from "../util/filesystem"
 
 const MAX_LINE_LENGTH = 2000
 
@@ -19,7 +20,7 @@ export const GrepTool = Tool.define("grep", {
       throw new Error("pattern is required")
     }
 
-    const searchPath = params.path || Instance.directory
+    const searchPath = params.path ? Filesystem.toNativePath(params.path) : Instance.directory
 
     const rgPath = await Ripgrep.filepath()
     const args = ["-nH", "--field-match-separator=|", "--regexp", params.pattern]

packages/opencode/src/tool/ls.ts

@@ -4,6 +4,7 @@ import * as path from "path"
 import DESCRIPTION from "./ls.txt"
 import { Instance } from "../project/instance"
 import { Ripgrep } from "../file/ripgrep"
+import { Filesystem } from "../util/filesystem"
 
 export const IGNORE_PATTERNS = [
   "node_modules/",
@@ -41,7 +42,7 @@ export const ListTool = Tool.define("list", {
     ignore: z.array(z.string()).describe("List of glob patterns to ignore").optional(),
   }),
   async execute(params) {
-    const searchPath = path.resolve(Instance.directory, params.path || ".")
+    const searchPath = path.resolve(Instance.directory, Filesystem.toNativePath(params.path || "."))
 
     const ignoreGlobs = IGNORE_PATTERNS.map((p) => `!${p}*`).concat(params.ignore?.map((p) => `!${p}`) || [])
     const files = []
@@ -99,7 +100,7 @@ export const ListTool = Tool.define("list", {
     const output = `${searchPath}/\n` + renderDir(".", 0)
 
     return {
-      title: path.relative(Instance.worktree, searchPath),
+      title: Filesystem.safeRelative(Instance.worktree, searchPath),
       metadata: {
         count: files.length,
         truncated: files.length >= LIMIT,

packages/opencode/src/tool/patch.ts

@@ -219,7 +219,7 @@ export const PatchTool = Tool.define("patch", {
     }
 
     // Generate output summary
-    const relativePaths = changedFiles.map((filePath) => path.relative(Instance.worktree, filePath))
+    const relativePaths = changedFiles.map((filePath) => Filesystem.safeRelative(Instance.worktree, filePath))
     const summary = `${fileChanges.length} files changed`
 
     return {

packages/opencode/src/tool/read.ts

@@ -23,11 +23,11 @@ export const ReadTool = Tool.define("read", {
     limit: z.coerce.number().describe("The number of lines to read (defaults to 2000)").optional(),
   }),
   async execute(params, ctx) {
-    let filepath = params.filePath
+    let filepath = Filesystem.toNativePath(params.filePath)
     if (!path.isAbsolute(filepath)) {
       filepath = path.join(process.cwd(), filepath)
     }
-    const title = path.relative(Instance.worktree, filepath)
+    const title = Filesystem.safeRelative(Instance.worktree, filepath)
     const agent = await Agent.get(ctx.agent)
 
     if (!ctx.extra?.["bypassCwdCheck"] && !Filesystem.contains(Instance.directory, filepath)) {

packages/opencode/src/tool/write.ts

@@ -23,7 +23,8 @@ export const WriteTool = Tool.define("write", {
   async execute(params, ctx) {
     const agent = await Agent.get(ctx.agent)
 
-    const filepath = path.isAbsolute(params.filePath) ? params.filePath : path.join(Instance.directory, params.filePath)
+    const rawPath = Filesystem.toNativePath(params.filePath)
+    const filepath = path.isAbsolute(rawPath) ? rawPath : path.join(Instance.directory, rawPath)
     if (!Filesystem.contains(Instance.directory, filepath)) {
       const parentDir = path.dirname(filepath)
       if (agent.permission.external_directory === "ask") {
@@ -98,7 +99,7 @@ export const WriteTool = Tool.define("write", {
     }
 
     return {
-      title: path.relative(Instance.worktree, filepath),
+      title: Filesystem.safeRelative(Instance.worktree, filepath),
       metadata: {
         diagnostics,
         filepath,

packages/opencode/src/util/filesystem.ts

@@ -3,11 +3,19 @@ import { exists } from "fs/promises"
 import { dirname, join, relative } from "path"
 
 export namespace Filesystem {
-  /**
-   * On Windows, normalize a path to its canonical casing using the filesystem.
-   * This is needed because Windows paths are case-insensitive but LSP servers
-   * may return paths with different casing than what we send them.
-   */
+  // Convert MSYS2/Git Bash/Cygwin paths to Windows paths (no-op on other platforms)
+  export function toNativePath(p: string): string {
+    if (process.platform !== "win32") return p
+    if (/^\/[a-zA-Z]\//.test(p)) {
+      return p.replace(/^\/([a-zA-Z])\//, (_, d) => `${d.toUpperCase()}:\\`).replace(/\//g, "\\")
+    }
+    if (/^\/cygdrive\/[a-zA-Z]\//.test(p)) {
+      return p.replace(/^\/cygdrive\/([a-zA-Z])\//, (_, d) => `${d.toUpperCase()}:\\`).replace(/\//g, "\\")
+    }
+    return p
+  }
+
+  // Normalize path casing on Windows using filesystem
   export function normalizePath(p: string): string {
     if (process.platform !== "win32") return p
     try {
@@ -26,6 +34,19 @@ export namespace Filesystem {
     return !relative(parent, child).startsWith("..")
   }
 
+  // Safe relative path - returns absolute if cross-drive or too many parent traversals
+  export function safeRelative(from: string, to: string): string {
+    if (process.platform === "win32") {
+      const fromDrive = from.match(/^([a-zA-Z]):/)?.[1]?.toUpperCase()
+      const toDrive = to.match(/^([a-zA-Z]):/)?.[1]?.toUpperCase()
+      if (fromDrive && toDrive && fromDrive !== toDrive) return to
+    }
+    const rel = relative(from, to)
+    // If path has 3+ parent traversals, use absolute path instead
+    if (/^(\.\.[/\\]){3,}/.test(rel)) return to
+    return rel
+  }
+
   export async function findUp(target: string, start: string, stop?: string) {
     let current = start
     const result = []