fix: disable experimental API betas by default, reduce side query token usage, standardize Headers type (#281)

* fix: disable experimental API betas by default to prevent 500 errors

Tool search (defer_loading), global cache scope, and context management
betas require internal Anthropic server-side support. External accounts
receive 500 Internal Server Error when these are sent.

Set CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=true by default in the CLI
entrypoint. Users with internal access can opt back in with =false.

Also includes: cache key stability fixes (Sonnet 1M latch, system-before-
messages key ordering, resume fingerprint isMeta skip), sideQuery default
cleanup, and /dream command.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* refactor: standardize API headers to Headers type and enable tengu feature flags by default

* fix: address PR review — dream lock, MCP betas guard, redundant Partial

- Call recordConsolidation() programmatically in /dream instead of
  delegating to model prompt (unreliable)
- Add CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS guard to MCP entrypoint
  (was only in CLI entrypoint, causing 500s in MCP server mode)
- Remove redundant ? markers from SecretValueSource Partial<{}> type

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/commands/dream/dream.ts

@@ -0,0 +1,68 @@
+import type { ContentBlockParam } from '@anthropic-ai/sdk/resources/messages.mjs'
+import type { Command } from '../../commands.js'
+import { isAutoMemoryEnabled, getAutoMemPath } from '../../memdir/paths.js'
+import { getProjectDir } from '../../utils/sessionStorage.js'
+import { getOriginalCwd, getSessionId } from '../../bootstrap/state.js'
+import { buildConsolidationPrompt } from '../../services/autoDream/consolidationPrompt.js'
+import {
+  readLastConsolidatedAt,
+  listSessionsTouchedSince,
+  recordConsolidation,
+} from '../../services/autoDream/consolidationLock.js'
+
+const command = {
+  type: 'prompt',
+  name: 'dream',
+  description:
+    'Run memory consolidation — synthesize recent sessions into durable memories',
+  isEnabled: () => isAutoMemoryEnabled(),
+  progressMessage: 'consolidating memories',
+  contentLength: 0,
+  source: 'builtin',
+  async getPromptForCommand(): Promise<ContentBlockParam[]> {
+    const memoryRoot = getAutoMemPath()
+    const transcriptDir = getProjectDir(getOriginalCwd())
+
+    let lastAt: number
+    try {
+      lastAt = await readLastConsolidatedAt()
+    } catch {
+      lastAt = 0
+    }
+
+    let sessionIds: string[]
+    try {
+      sessionIds = await listSessionsTouchedSince(lastAt)
+    } catch {
+      sessionIds = []
+    }
+
+    const currentSession = getSessionId()
+    sessionIds = sessionIds.filter(id => id !== currentSession)
+
+    if (sessionIds.length === 0) {
+      sessionIds = [currentSession]
+    }
+
+    const hoursSince =
+      lastAt > 0
+        ? `${((Date.now() - lastAt) / 3_600_000).toFixed(1)}h ago`
+        : 'never'
+
+    const extra = `
+**Manually triggered by user via /dream.**
+
+Sessions since last consolidation (${sessionIds.length}, last run: ${hoursSince}):
+${sessionIds.map(id => `- ${id}`).join('\n')}`
+
+    const prompt = buildConsolidationPrompt(memoryRoot, transcriptDir, extra)
+
+    // Record consolidation timestamp programmatically so auto-dream
+    // knows when the last manual run happened.
+    await recordConsolidation()
+
+    return [{ type: 'text', text: prompt }]
+  },
+} satisfies Command
+
+export default command

src/commands/dream/index.ts

@@ -0,0 +1 @@
+export { default } from './dream.js'