refactor: codebase audit cleanup — dead code, dedup, module splits

Multi-agent audit + aggressive cleanup across server/web/coder/booterm,
delivered behind a DEFER discipline so none of the in-flight files were
touched. Removes dead code/deps/columns, dedups server + coder helpers,
and splits the oversized modules (tools.ts, opencode-server.ts,
sentinel-summaries, turn.ts, TerminalPane.tsx) behind stable contracts.
Adds 78 parity/unit tests (server 587, coder 323); fixes two latent bugs
(ChatPane queue keys, FileViewerOverlay blank-line parity).

Intended tag: v2.7.12-audit-cleanup.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/server/src/services/__tests__/inference-helpers.test.ts

@@ -0,0 +1,149 @@
+import { describe, expect, it, vi, afterEach } from 'vitest';
+import { samplerOptsFromAgent } from '../inference/stream-phase.js';
+import { createContentFlusher } from '../inference/content-flusher.js';
+import type { Sql } from '../../db.js';
+import type { Agent } from '../../types/api.js';
+
+const BASE_AGENT: Agent = {
+  id: 'test-agent',
+  name: 'Test',
+  description: 'test',
+  system_prompt: '',
+  temperature: 0.7,
+  top_p: null,
+  top_k: null,
+  min_p: null,
+  presence_penalty: null,
+  top_n_sigma: null,
+  dry_multiplier: null,
+  dry_base: null,
+  dry_allowed_length: null,
+  dry_penalty_last_n: null,
+  tools: ['view_file'],
+  model: null,
+  source: 'global',
+  max_tool_calls: null,
+  steps: null,
+  llama_extra_args: null,
+};
+
+describe('samplerOptsFromAgent', () => {
+  it('maps every nullable sampler field to undefined when agent is null', () => {
+    expect(samplerOptsFromAgent(null)).toEqual({
+      temperature: undefined,
+      top_p: undefined,
+      top_k: undefined,
+      min_p: undefined,
+      presence_penalty: undefined,
+      top_n_sigma: undefined,
+      dry_multiplier: undefined,
+      dry_base: undefined,
+      dry_allowed_length: undefined,
+      dry_penalty_last_n: undefined,
+    });
+  });
+
+  it('strips null sampler fields to undefined but keeps numeric values', () => {
+    const agent: Agent = {
+      ...BASE_AGENT,
+      temperature: 0.5,
+      top_p: 0.9,
+      top_k: null,
+      min_p: 0.05,
+      presence_penalty: null,
+      top_n_sigma: 1,
+      dry_multiplier: null,
+      dry_base: 1.75,
+      dry_allowed_length: null,
+      dry_penalty_last_n: 256,
+    };
+    expect(samplerOptsFromAgent(agent)).toEqual({
+      temperature: 0.5,
+      top_p: 0.9,
+      top_k: undefined,
+      min_p: 0.05,
+      presence_penalty: undefined,
+      top_n_sigma: 1,
+      dry_multiplier: undefined,
+      dry_base: 1.75,
+      dry_allowed_length: undefined,
+      dry_penalty_last_n: 256,
+    });
+  });
+
+  it('never includes a tools field (callers add it)', () => {
+    expect('tools' in samplerOptsFromAgent(BASE_AGENT)).toBe(false);
+  });
+});
+
+describe('createContentFlusher', () => {
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  // A tagged-template stub matching postgres' sql`...` shape. Records the
+  // interpolated content snapshot (values[0]) of each UPDATE.
+  function makeSqlSpy() {
+    const writes: string[] = [];
+    const sql = ((_strings: TemplateStringsArray, ...values: unknown[]) => {
+      writes.push(values[0] as string);
+      return Promise.resolve([]);
+    }) as unknown as Sql;
+    return { sql, writes };
+  }
+
+  it('debounces: many scheduleFlush calls in one window produce one write', async () => {
+    vi.useFakeTimers();
+    const { sql, writes } = makeSqlSpy();
+    let content = '';
+    const flusher = createContentFlusher(sql, 'msg-1', () => content, 500);
+
+    content = 'a';
+    flusher.scheduleFlush();
+    content = 'ab';
+    flusher.scheduleFlush();
+    content = 'abc';
+    flusher.scheduleFlush();
+
+    expect(writes).toHaveLength(0); // nothing before the interval elapses
+    vi.advanceTimersByTime(500);
+    await flusher.drain();
+
+    expect(writes).toHaveLength(1);
+    // snapshot is read at fire time → latest content, not the value at schedule time
+    expect(writes[0]).toBe('abc');
+  });
+
+  it('arms a fresh timer after a flush fires', async () => {
+    vi.useFakeTimers();
+    const { sql, writes } = makeSqlSpy();
+    let content = 'one';
+    const flusher = createContentFlusher(sql, 'msg-1', () => content, 500);
+
+    flusher.scheduleFlush();
+    vi.advanceTimersByTime(500);
+    await Promise.resolve();
+
+    content = 'two';
+    flusher.scheduleFlush();
+    vi.advanceTimersByTime(500);
+    await flusher.drain();
+
+    expect(writes).toEqual(['one', 'two']);
+  });
+
+  it('drain cancels a pending timer without performing a final flush', async () => {
+    vi.useFakeTimers();
+    const { sql, writes } = makeSqlSpy();
+    let content = 'pending';
+    const flusher = createContentFlusher(sql, 'msg-1', () => content, 500);
+
+    flusher.scheduleFlush();
+    // Drain before the timer fires — the pending flush is cancelled, not forced.
+    await flusher.drain();
+    vi.advanceTimersByTime(500);
+    await Promise.resolve();
+
+    expect(writes).toHaveLength(0);
+  });
+});