diff --git a/packages/ui/src/components/prompt-input/usePromptPicker.ts b/packages/ui/src/components/prompt-input/usePromptPicker.ts
index ada32cc9..98e53bc6 100644
--- a/packages/ui/src/components/prompt-input/usePromptPicker.ts
+++ b/packages/ui/src/components/prompt-input/usePromptPicker.ts
@@ -1,9 +1,10 @@
 import { createSignal, type Accessor, type Setter } from "solid-js"
 import type { Command as SDKCommand } from "@opencode-ai/sdk/v2"
 import type { Agent } from "../../types/session"
-import { createAgentAttachment, createFileAttachment } from "../../types/attachment"
+import { createAgentAttachment, createFileAttachment, createTextAttachment } from "../../types/attachment"
 import { addAttachment, getAttachments } from "../../stores/attachments"
 import type { PickerMode } from "./types"
+import type { PickerSelectAction } from "../unified-picker"
 
 type PickerItem =
   | { type: "agent"; agent: Agent }
@@ -37,7 +38,7 @@ type PromptPickerController = {
   setIgnoredAtPositions: Setter<Set<number>>
 
   handleInput: (e: Event) => void
-  handlePickerSelect: (item: PickerItem) => void
+  handlePickerSelect: (item: PickerItem, action: PickerSelectAction) => void
   handlePickerClose: () => void
 }
 
@@ -103,10 +104,11 @@ export function usePromptPicker(options: PromptPickerOptions): PromptPickerContr
     setAtPosition(null)
   }
 
-  function handlePickerSelect(item: PickerItem) {
+  function handlePickerSelect(item: PickerItem, action: PickerSelectAction) {
     const textarea = options.getTextarea()
 
     if (item.type === "command") {
+      // For commands, Tab/Enter/Shift+Enter/click all mean "select".
       const name = item.command.name
       const currentPrompt = options.prompt()
 
@@ -128,6 +130,7 @@ export function usePromptPicker(options: PromptPickerOptions): PromptPickerContr
         }
       }, 0)
     } else if (item.type === "agent") {
+      // For agents, Tab/Enter/Shift+Enter/click all mean "select".
       const agentName = item.agent.name
       const existingAttachments = getAttachments(options.instanceId(), options.sessionId())
       const alreadyAttached = existingAttachments.some(
@@ -163,76 +166,144 @@ export function usePromptPicker(options: PromptPickerOptions): PromptPickerContr
       const relativePath = item.file.relativePath ?? displayPath
       const isFolder = item.file.isDirectory ?? displayPath.endsWith("/")
 
-      if (isFolder) {
-        const currentPrompt = options.prompt()
-        const pos = atPosition()
-        const cursorPos = textarea?.selectionStart || 0
-        const folderMention =
-          relativePath === "." || relativePath === ""
-            ? "/"
-            : relativePath.replace(/\/+$/, "") + "/"
-
-        if (pos !== null) {
-          const before = currentPrompt.substring(0, pos + 1)
-          const after = currentPrompt.substring(cursorPos)
-          const newPrompt = before + folderMention + after
-          options.setPrompt(newPrompt)
-          setSearchQuery(folderMention)
-
-          setTimeout(() => {
-            const nextTextarea = options.getTextarea()
-            if (nextTextarea) {
-              const newCursorPos = pos + 1 + folderMention.length
-              nextTextarea.setSelectionRange(newCursorPos, newCursorPos)
-            }
-          }, 0)
-        }
-
-        return
-      }
-
-      const normalizedPath = relativePath.replace(/\/+$/, "") || relativePath
-      const pathSegments = normalizedPath.split("/")
-      const filename = (() => {
-        const candidate = pathSegments[pathSegments.length - 1] || normalizedPath
-        return candidate === "." ? "/" : candidate
-      })()
-
-      const existingAttachments = getAttachments(options.instanceId(), options.sessionId())
-      const alreadyAttached = existingAttachments.some(
-        (att) => att.source.type === "file" && att.source.path === normalizedPath,
-      )
-
-      if (!alreadyAttached) {
-        const attachment = createFileAttachment(
-          normalizedPath,
-          filename,
-          "text/plain",
-          undefined,
-          options.instanceFolder(),
-        )
-        addAttachment(options.instanceId(), options.sessionId(), attachment)
-      }
-
-      const currentPrompt = options.prompt()
       const pos = atPosition()
       const cursorPos = textarea?.selectionStart || 0
 
-      if (pos !== null) {
+      const replaceMentionToken = (mentionText: string, opts?: { trailingSpace?: boolean }) => {
+        if (pos === null) return
+        const currentPrompt = options.prompt()
         const before = currentPrompt.substring(0, pos)
         const after = currentPrompt.substring(cursorPos)
-        const attachmentText = `@${normalizedPath}`
-        const newPrompt = before + attachmentText + " " + after
-        options.setPrompt(newPrompt)
+        const suffix = opts?.trailingSpace ? " " : ""
+        const nextPrompt = before + mentionText + suffix + after
+        options.setPrompt(nextPrompt)
 
         setTimeout(() => {
           const nextTextarea = options.getTextarea()
-          if (nextTextarea) {
-            const newCursorPos = pos + attachmentText.length + 1
-            nextTextarea.setSelectionRange(newCursorPos, newCursorPos)
-          }
+          if (!nextTextarea) return
+          const nextCursorPos = pos + mentionText.length + suffix.length
+          nextTextarea.setSelectionRange(nextCursorPos, nextCursorPos)
         }, 0)
       }
+
+      const replaceMentionQueryAfterAt = (value: string) => {
+        // Replaces only the query after '@' (keeps the '@' itself). Used for directory navigation.
+        if (pos === null) return
+        const currentPrompt = options.prompt()
+        const before = currentPrompt.substring(0, pos + 1)
+        const after = currentPrompt.substring(cursorPos)
+        const nextPrompt = before + value + after
+        options.setPrompt(nextPrompt)
+
+        setTimeout(() => {
+          const nextTextarea = options.getTextarea()
+          if (!nextTextarea) return
+          const nextCursorPos = pos + 1 + value.length
+          nextTextarea.setSelectionRange(nextCursorPos, nextCursorPos)
+        }, 0)
+      }
+
+      const folderMention =
+        relativePath === "." || relativePath === ""
+          ? "/"
+          : relativePath.replace(/\/+$/, "") + "/"
+
+      const normalizedFolderPath = (() => {
+        const trimmed = relativePath.replace(/\/+$/, "")
+        return trimmed.length > 0 ? trimmed : "."
+      })()
+
+      const addPathOnlyAttachment = (value: string) => {
+        const display = `path: ${value}`
+        const filename = value
+        const existing = getAttachments(options.instanceId(), options.sessionId())
+        const alreadyAttached = existing.some(
+          (att) => att.source.type === "text" && att.source.value === value && att.display === display,
+        )
+        if (!alreadyAttached) {
+          addAttachment(options.instanceId(), options.sessionId(), createTextAttachment(value, display, filename))
+        }
+      }
+
+      if (isFolder) {
+        if (action === "tab") {
+          // TAB on directory: autocomplete directory name and show its contents.
+          replaceMentionQueryAfterAt(folderMention)
+          setSearchQuery(folderMention)
+          return
+        }
+
+        const mentionText = `@${folderMention}`
+
+        if (action === "shiftEnter") {
+          // SHIFT+ENTER on directory: attach path as text only.
+          addPathOnlyAttachment(folderMention)
+          replaceMentionToken(mentionText, { trailingSpace: true })
+        } else {
+          // ENTER/click on directory: attach as a file part pointing at a file:// directory URL.
+          const dirLabel =
+            normalizedFolderPath === "." ? "/" : normalizedFolderPath.split("/").pop() || normalizedFolderPath
+          const dirFilename = dirLabel.endsWith("/") ? dirLabel : `${dirLabel}/`
+
+          const existingAttachments = getAttachments(options.instanceId(), options.sessionId())
+          const alreadyAttached = existingAttachments.some(
+            (att) => att.source.type === "file" && att.source.path === normalizedFolderPath && att.source.mime === "inode/directory",
+          )
+
+          if (!alreadyAttached) {
+            const attachment = createFileAttachment(
+              normalizedFolderPath,
+              dirFilename,
+              "inode/directory",
+              undefined,
+              options.instanceFolder(),
+            )
+            addAttachment(options.instanceId(), options.sessionId(), attachment)
+          }
+
+          replaceMentionToken(mentionText, { trailingSpace: true })
+        }
+      } else {
+        const normalizedPath = relativePath.replace(/\/+$/, "") || relativePath
+
+        if (action === "tab") {
+          // TAB on file: autocomplete the file path but do not attach.
+          replaceMentionToken(`@${normalizedPath}`)
+          setSearchQuery(normalizedPath)
+          return
+        }
+
+        if (action === "shiftEnter") {
+          // SHIFT+ENTER on file: attach path as text only.
+          addPathOnlyAttachment(normalizedPath)
+          replaceMentionToken(`@${normalizedPath}`, { trailingSpace: true })
+        } else {
+          // ENTER/click on file: attach file (existing behavior).
+          const pathSegments = normalizedPath.split("/")
+          const filename = (() => {
+            const candidate = pathSegments[pathSegments.length - 1] || normalizedPath
+            return candidate === "." ? "/" : candidate
+          })()
+
+          const existingAttachments = getAttachments(options.instanceId(), options.sessionId())
+          const alreadyAttached = existingAttachments.some(
+            (att) => att.source.type === "file" && att.source.path === normalizedPath,
+          )
+
+          if (!alreadyAttached) {
+            const attachment = createFileAttachment(
+              normalizedPath,
+              filename,
+              "text/plain",
+              undefined,
+              options.instanceFolder(),
+            )
+            addAttachment(options.instanceId(), options.sessionId(), attachment)
+          }
+
+          replaceMentionToken(`@${normalizedPath}`, { trailingSpace: true })
+        }
+      }
     }
 
     setShowPicker(false)
diff --git a/packages/ui/src/components/unified-picker.tsx b/packages/ui/src/components/unified-picker.tsx
index 0abc00be..7284d145 100644
--- a/packages/ui/src/components/unified-picker.tsx
+++ b/packages/ui/src/components/unified-picker.tsx
@@ -74,10 +74,12 @@ type PickerItem =
   | { type: "file"; file: FileItem }
   | { type: "command"; command: SDKCommand }
 
+export type PickerSelectAction = "click" | "tab" | "enter" | "shiftEnter"
+
 interface UnifiedPickerProps {
   open: boolean
   mode?: "mention" | "command"
-  onSelect: (item: PickerItem) => void
+  onSelect: (item: PickerItem, action: PickerSelectAction) => void
   onClose: () => void
   agents: Agent[]
   commands?: SDKCommand[]
@@ -356,7 +358,7 @@ const UnifiedPicker: Component<UnifiedPickerProps> = (props) => {
   }
 
   function handleSelect(item: PickerItem) {
-    props.onSelect(item)
+    props.onSelect(item, "click")
   }
 
   function handleKeyDown(e: KeyboardEvent) {
@@ -379,7 +381,8 @@ const UnifiedPicker: Component<UnifiedPickerProps> = (props) => {
       e.stopPropagation()
       const selected = items[selectedIndex()]
       if (selected) {
-        handleSelect(selected)
+        const action: PickerSelectAction = e.key === "Tab" ? "tab" : e.shiftKey ? "shiftEnter" : "enter"
+        props.onSelect(selected, action)
       }
     } else if (e.key === "Escape") {
       e.preventDefault()
@@ -443,7 +446,7 @@ const UnifiedPicker: Component<UnifiedPickerProps> = (props) => {
                   <div
                     class={`dropdown-item ${isSelected() ? "dropdown-item-highlight" : ""}`}
                     data-picker-selected={isSelected()}
-                    onClick={() => handleSelect({ type: "command", command })}
+                    onClick={() => props.onSelect({ type: "command", command }, "click")}
                   >
                     <div class="flex items-start gap-2">
                       <svg class="dropdown-icon-accent h-4 w-4 mt-0.5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
@@ -479,7 +482,7 @@ const UnifiedPicker: Component<UnifiedPickerProps> = (props) => {
                       itemIndex === selectedIndex() ? "dropdown-item-highlight" : ""
                     }`}
                     data-picker-selected={itemIndex === selectedIndex()}
-                    onClick={() => handleSelect({ type: "agent", agent })}
+                    onClick={() => props.onSelect({ type: "agent", agent }, "click")}
                   >
                     <div class="flex items-start gap-2">
                       <svg
@@ -535,7 +538,7 @@ const UnifiedPicker: Component<UnifiedPickerProps> = (props) => {
                       itemIndex === selectedIndex() ? "dropdown-item-highlight" : ""
                     }`}
                     data-picker-selected={itemIndex === selectedIndex()}
-                    onClick={() => handleSelect({ type: "file", file })}
+                    onClick={() => props.onSelect({ type: "file", file }, "click")}
                   >
                     <div class="flex items-center gap-2 text-sm">
                       <Show