feat(codex): support slash controls and skill discovery (#545)

* feat(codex): resolve slash controls before sending to Codex

* feat(codex): discover commands and skills

* fix(codex): handle slash commands before attachments

* fix(codex): block remaining unsupported built-ins

web/src/components/AssistantChat/HappyComposer.tsx

@@ -199,20 +199,12 @@ export function HappyComposer(props: {
             markSkillUsed(suggestion.text.slice(1))
         }
 
-        // For Codex user prompts with content, expand the content instead of command name
-        let textToInsert = suggestion.text
-        let addSpace = true
-        if (agentFlavor === 'codex' && suggestion.source !== 'builtin' && suggestion.content) {
-            textToInsert = suggestion.content
-            addSpace = false
-        }
-
         const result = applySuggestion(
             inputState.text,
             inputState.selection,
-            textToInsert,
+            suggestion.text,
             autocompletePrefixes,
-            addSpace
+            true
         )
 
         api.composer().setText(result.text)
@@ -233,7 +225,7 @@ export function HappyComposer(props: {
         }, 0)
 
         haptic('light')
-    }, [api, suggestions, inputState, autocompletePrefixes, haptic, agentFlavor])
+    }, [api, suggestions, inputState, autocompletePrefixes, haptic])
 
     const abortDisabled = controlsDisabled || isAborting || !threadIsRunning
     const switchDisabled = controlsDisabled || isSwitching || !controlledByUser

web/src/components/SessionChat.tsx

@@ -20,8 +20,6 @@ import { HappyComposer } from '@/components/AssistantChat/HappyComposer'
 import { HappyThread } from '@/components/AssistantChat/HappyThread'
 import { useHappyRuntime } from '@/lib/assistant-runtime'
 import { createAttachmentAdapter } from '@/lib/attachmentAdapter'
-import { findUnsupportedCodexBuiltinSlashCommand } from '@/lib/codexSlashCommands'
-import { useToast } from '@/lib/toast-context'
 import { useTranslation } from '@/lib/use-translation'
 import { SessionHeader } from '@/components/SessionHeader'
 import { TeamPanel } from '@/components/TeamPanel'
@@ -67,7 +65,6 @@ export function SessionChat(props: {
     availableSlashCommands?: readonly SlashCommand[]
 }) {
     const { haptic } = usePlatform()
-    const { addToast } = useToast()
     const { t } = useTranslation()
     const navigate = useNavigate()
     const sessionInactive = !props.session.active
@@ -349,26 +346,9 @@ export function SessionChat(props: {
     }, [navigate, props.session.id])
 
     const handleSend = useCallback((text: string, attachments?: AttachmentMetadata[]) => {
-        if (agentFlavor === 'codex') {
-            const unsupportedCommand = findUnsupportedCodexBuiltinSlashCommand(
-                text,
-                props.availableSlashCommands ?? []
-            )
-            if (unsupportedCommand) {
-                haptic.notification('error')
-                addToast({
-                    title: t('composer.codexSlashUnsupported.title'),
-                    body: t('composer.codexSlashUnsupported.body', { command: `/${unsupportedCommand}` }),
-                    sessionId: props.session.id,
-                    url: `/sessions/${props.session.id}`
-                })
-                return
-            }
-        }
-
         props.onSend(text, attachments)
         setForceScrollToken((token) => token + 1)
-    }, [agentFlavor, props.availableSlashCommands, props.onSend, props.session.id, addToast, haptic, t])
+    }, [props.onSend])
 
     const attachmentAdapter = useMemo(() => {
         if (!props.session.active) {

web/src/hooks/queries/useSlashCommands.ts

@@ -49,16 +49,18 @@ export function useSlashCommands(
         retry: false, // Don't retry RPC failures
     })
 
-    // Merge built-in commands with user-defined and plugin commands from API
+    // Merge local built-ins with commands discovered by the active CLI.
+    // The CLI can expose agent-specific built-ins plus user/plugin/project commands;
+    // keep local built-ins as an offline fallback, then append/override from RPC.
     const commands = useMemo(() => {
         const builtin = getBuiltinSlashCommands(agentType)
 
-        // If API succeeded, add user-defined and plugin commands
         if (query.data?.success && query.data.commands) {
-            const extraCommands = query.data.commands.filter(
-                cmd => cmd.source === 'user' || cmd.source === 'plugin' || cmd.source === 'project'
-            )
-            return [...builtin, ...extraCommands]
+            const commandMap = new Map<string, SlashCommand>()
+            for (const command of [...builtin, ...query.data.commands]) {
+                commandMap.set(command.name, command)
+            }
+            return Array.from(commandMap.values())
         }
 
         // Fallback to built-in commands only

web/src/lib/codexSlashCommands.test.ts

@@ -2,14 +2,19 @@ import { describe, expect, it } from 'vitest'
 import { findUnsupportedCodexBuiltinSlashCommand, getBuiltinSlashCommands } from './codexSlashCommands'
 
 describe('getBuiltinSlashCommands', () => {
-    it('does not expose codex built-ins in remote web mode', () => {
-        expect(getBuiltinSlashCommands('codex')).toEqual([])
+    it('exposes HAPI-supported codex built-ins in remote web mode', () => {
+        expect(getBuiltinSlashCommands('codex').map((command) => command.name)).toEqual(expect.arrayContaining([
+            'plan',
+            'status',
+            'execute',
+            'effort',
+            'permission',
+        ]))
     })
 })
 
 describe('findUnsupportedCodexBuiltinSlashCommand', () => {
     it('detects unsupported codex built-ins', () => {
-        expect(findUnsupportedCodexBuiltinSlashCommand('/status', [])).toBe('status')
         expect(findUnsupportedCodexBuiltinSlashCommand('  /diff ', [])).toBe('diff')
     })
 

web/src/lib/codexSlashCommands.ts

@@ -11,9 +11,18 @@ const BUILTIN_COMMANDS: Record<string, SlashCommand[]> = {
         { name: 'stats', description: 'Show your Claude Code usage statistics and activity', source: 'builtin' },
         { name: 'status', description: 'Show Claude Code status including version, model, account, and API connectivity', source: 'builtin' },
     ],
-    // Codex remote turns send slash-prefixed input as plain text to app-server.
-    // Hide built-ins here until remote slash command execution is implemented end-to-end.
-    codex: [],
+    codex: [
+        { name: 'help', description: 'Show supported HAPI Codex slash commands', source: 'builtin' },
+        { name: 'plan', description: 'Enable plan mode; use /plan off to return to default', source: 'builtin' },
+        { name: 'default', description: 'Return Codex collaboration mode to default', source: 'builtin' },
+        { name: 'execute', description: 'Return Codex collaboration mode to default', source: 'builtin' },
+        { name: 'status', description: 'Show current Codex session config', source: 'builtin' },
+        { name: 'model', description: 'Show or set Codex model, e.g. /model gpt-5.5', source: 'builtin' },
+        { name: 'reasoning', description: 'Show or set reasoning effort', source: 'builtin' },
+        { name: 'effort', description: 'Alias for /reasoning', source: 'builtin' },
+        { name: 'permissions', description: 'Show or set permission mode', source: 'builtin' },
+        { name: 'permission', description: 'Alias for /permissions', source: 'builtin' },
+    ],
     gemini: [
         { name: 'about', description: 'Show version info', source: 'builtin' },
         { name: 'clear', description: 'Clear the screen and conversation history', source: 'builtin' },
@@ -29,7 +38,6 @@ const UNSUPPORTED_CODEX_BUILTIN_COMMANDS = new Set([
     'compat',
     'undo',
     'diff',
-    'status',
 ])
 
 export function getBuiltinSlashCommands(agentType: string): SlashCommand[] {