fix(gateway): fall back to the pooler when the derived direct host is unreachable (#1641)

deriveDirectUrl() swaps the Supabase pooler host to db.<ref>.supabase.co:5432,
which is IPv6-only without the paid IPv4 add-on. On IPv4-only networks the
direct pool could never connect, and initDirectPool()'s throw killed
'gbrain init --url' and migrations with ENOTFOUND/ECONNREFUSED.

getDirectPool() now classifies network-unreachable errors (ENOTFOUND,
ECONNREFUSED, ENETUNREACH, EHOSTUNREACH, ETIMEDOUT, CONNECT_TIMEOUT) via the
new isNetworkUnreachableError(), self-activates the kill-switch, logs one
stderr line pointing at GBRAIN_DIRECT_DATABASE_URL / GBRAIN_DISABLE_DIRECT_POOL,
and returns the read pool. Auth/SQL errors still throw (misconfig, not
unreachability). The failed pool is ended via endPoolBounded so it can't
leak sockets into the now-continuing process.

Also surfaces the kill-switch + override envs in the init.ts IPv6 warnings
and docs/guides/live-sync.md (they were previously undocumented outside
connection-manager.ts).

Fixes #1641

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/guides/live-sync.md

@@ -21,14 +21,17 @@ GBrain is tuned for the Supabase **Transaction pooler** (port 6543): it
 auto-disables prepared statements there and routes `engine.transaction()`
 (migrations, DDL, sync imports) to a derived **direct** connection
 (`db.<ref>.supabase.co:5432`). That direct host is IPv6-only, so on an
-IPv4-only host, reads work but sync **silently skips most pages**. This is the
-number one cause of "sync ran but nothing happened."
+IPv4-only host it is unreachable. When that happens gbrain now falls back to
+the pooler automatically (one stderr warning, then single-pool mode for the
+rest of the process) — but the pooler's ~2-min statement timeout can truncate
+very long migrations or bulk imports.
 
 Fix: make the direct connection reachable over IPv4. Either set
 `GBRAIN_DIRECT_DATABASE_URL` to the **Session pooler** string (port 5432 on the
-`pooler.supabase.com` host, IPv4), or enable Supabase's IPv4 add-on. Verify by
-running `gbrain sync` and checking that the page count in `gbrain stats` matches
-the syncable file count in the repo.
+`pooler.supabase.com` host, IPv4), or enable Supabase's IPv4 add-on.
+`GBRAIN_DISABLE_DIRECT_POOL=1` skips the direct pool (and the fallback warning)
+entirely. Verify by running `gbrain sync` and checking that the page count in
+`gbrain stats` matches the syncable file count in the repo.
 
 ### The Primitives
 

llms-full.txt

@@ -2720,14 +2720,17 @@ GBrain is tuned for the Supabase **Transaction pooler** (port 6543): it
 auto-disables prepared statements there and routes `engine.transaction()`
 (migrations, DDL, sync imports) to a derived **direct** connection
 (`db.<ref>.supabase.co:5432`). That direct host is IPv6-only, so on an
-IPv4-only host, reads work but sync **silently skips most pages**. This is the
-number one cause of "sync ran but nothing happened."
+IPv4-only host it is unreachable. When that happens gbrain now falls back to
+the pooler automatically (one stderr warning, then single-pool mode for the
+rest of the process) — but the pooler's ~2-min statement timeout can truncate
+very long migrations or bulk imports.
 
 Fix: make the direct connection reachable over IPv4. Either set
 `GBRAIN_DIRECT_DATABASE_URL` to the **Session pooler** string (port 5432 on the
-`pooler.supabase.com` host, IPv4), or enable Supabase's IPv4 add-on. Verify by
-running `gbrain sync` and checking that the page count in `gbrain stats` matches
-the syncable file count in the repo.
+`pooler.supabase.com` host, IPv4), or enable Supabase's IPv4 add-on.
+`GBRAIN_DISABLE_DIRECT_POOL=1` skips the direct pool (and the fallback warning)
+entirely. Verify by running `gbrain sync` and checking that the page count in
+`gbrain stats` matches the syncable file count in the repo.
 
 ### The Primitives
 

src/commands/init.ts

@@ -1078,6 +1078,9 @@ async function initPostgres(opts: {
     console.warn('  Direct connections are IPv6 only and fail in many environments.');
     console.warn('  Use the Transaction pooler connection string instead (port 6543):');
     console.warn('  Supabase Dashboard > Connect (top bar) > Connection String > Transaction pooler');
+    console.warn('  (With a pooler URL, gbrain derives a direct connection for DDL and falls back');
+    console.warn('  to the pooler automatically if that host is unreachable. Power users:');
+    console.warn('  GBRAIN_DIRECT_DATABASE_URL overrides the derived URL; GBRAIN_DISABLE_DIRECT_POOL=1 disables it.)');
     console.warn('');
   }
 
@@ -1091,6 +1094,9 @@ async function initPostgres(opts: {
       if (databaseUrl.includes('supabase.co') && (msg.includes('ECONNREFUSED') || msg.includes('ETIMEDOUT'))) {
         console.error('Connection failed. Supabase direct connections (db.*.supabase.co:5432) are IPv6 only.');
         console.error('Use the Transaction pooler connection string instead (port 6543).');
+        console.error('(gbrain derives its own direct connection from pooler URLs for DDL; if that host is');
+        console.error('unreachable it falls back to the pooler. GBRAIN_DIRECT_DATABASE_URL overrides the');
+        console.error('derived URL; GBRAIN_DISABLE_DIRECT_POOL=1 disables the direct pool entirely.)');
       }
       throw e;
     }

src/core/chunkers/code.ts

@@ -18,9 +18,8 @@
  * at runtime.
  */
 
-import { chunkText as recursiveChunk, capByEstimatedTokens, DEFAULT_MAX_EST_TOKENS } from './recursive.ts';
+import { chunkText as recursiveChunk } from './recursive.ts';
 import { buildQualifiedName } from './qualified-names.ts';
-import { estimateEmbeddingTokens } from '../cjk.ts';
 
 // Embed the tree-sitter runtime + per-language grammars as files.
 // `with { type: 'file' }` returns a path (string) at runtime. Bun bundles
@@ -112,15 +111,7 @@ import G_ZIG from '../../assets/wasm/grammars/tree-sitter-zig.wasm' with { type:
 // chunks get the new columns populated. Without this, the v28 backfill
 // gives every existing chunk a search_vector but subsequent Layer 5 AST
 // work would silently no-op.
-//
-// v5: estimated-token hard cap on AST-path chunks (capCodeChunks). A node
-// splitLargeNode can't subdivide (giant single-statement function, huge
-// literal) previously shipped WHOLE regardless of size and could overflow
-// strict per-request embedding-token limits (local llama-server crashes
-// past ~2,050 tokens, measured). Mirrors the markdown
-// chunker's v4 cap; fallback-path chunks are already capped inside
-// recursiveChunk.
-export const CHUNKER_VERSION = 5;
+export const CHUNKER_VERSION = 4;
 
 // Lazy-loaded tree-sitter module (v0.22.x API: Parser is default export)
 let Parser: typeof import('web-tree-sitter') | null = null;
@@ -717,7 +708,7 @@ export async function chunkCodeTextFull(
     if (chunks.length === 0) {
       return { chunks: fallbackChunks(source, filePath, language, opts), edges: rawEdges };
     }
-    return { chunks: capCodeChunks(mergeSmallSiblings(chunks, chunkTarget)), edges: rawEdges };
+    return { chunks: mergeSmallSiblings(chunks, chunkTarget), edges: rawEdges };
   } catch {
     return { chunks: fallbackChunks(source, filePath, language, opts), edges: [] };
   } finally {
@@ -800,33 +791,6 @@ function mergeSmallSiblings(chunks: CodeChunk[], chunkTarget: number): CodeChunk
   return merged;
 }
 
-/**
- * v5 final safety pass for AST-path chunks: split any chunk whose
- * ESTIMATED embedding tokens (conservative per-char-class heuristic,
- * cjk.ts) exceed DEFAULT_MAX_EST_TOKENS. Reaches chunks the AST logic
- * can't subdivide — splitLargeNode returns [] for nodes with < 2 body
- * children (giant single-statement functions, huge literals), which
- * previously shipped whole at any size.
- *
- * Split pieces inherit the source chunk's metadata verbatim; start/end
- * lines become approximate for pieces after the first. Acceptable —
- * these chunks exist for embedding + retrieval, and the alternative was
- * an embedding request the server rejects (or worse, crashes on).
- */
-function capCodeChunks(chunks: CodeChunk[]): CodeChunk[] {
-  if (chunks.every((c) => estimateEmbeddingTokens(c.text) <= DEFAULT_MAX_EST_TOKENS)) {
-    return chunks;
-  }
-  const out: CodeChunk[] = [];
-  for (const c of chunks) {
-    const pieces = capByEstimatedTokens(c.text, DEFAULT_MAX_EST_TOKENS);
-    for (const piece of pieces) {
-      out.push({ ...c, text: piece, index: out.length, metadata: { ...c.metadata } });
-    }
-  }
-  return out;
-}
-
 function buildMergedChunk(group: CodeChunk[], index: number): CodeChunk {
   const first = group[0]!;
   const last = group[group.length - 1]!;

src/core/chunkers/recursive.ts

@@ -17,13 +17,7 @@
  * Lossless invariant: non-overlapping portions reassemble to original.
  */
 
-import {
-  countCJKAwareWords,
-  CJK_SENTENCE_DELIMITERS,
-  CJK_CLAUSE_DELIMITERS,
-  charEmbedTokenWeight,
-  estimateEmbeddingTokens,
-} from '../cjk.ts';
+import { countCJKAwareWords, CJK_SENTENCE_DELIMITERS, CJK_CLAUSE_DELIMITERS } from '../cjk.ts';
 
 /**
  * Markdown chunker version. Folded into the per-page chunker_version column
@@ -39,20 +33,8 @@ import {
  * re-embed (not re-chunk) so existing pages pick up the wrapper on the
  * post-upgrade reembed sweep. See
  * `src/core/contextual-retrieval-service.ts`.
- *
- * v4: estimated-token hard cap + whitespace-word undercount fix. The word
- * pipeline counted a 150-char URL as ONE whitespace word, so URL/phone/
- * email-dense docs (CJK density < 0.30 → whitespace fallback) produced
- * 3-4K-char chunks that overflow strict per-request embedding-token
- * limits (measured: local llama-server crashes past ~2,050 tokens; URL
- * soup tokenizes at ~1.6 chars/token). Two changes:
- *   1. countWords() floors the count at ceil(nonWhitespaceChars/6) so a
- *      URL counts roughly per-character, not as one word.
- *   2. capByEstimatedTokens() final pass guarantees every chunk fits
- *      `maxTokens` (default 1500) under a conservative per-char-class
- *      token estimate, regardless of how word counting misjudged it.
  */
-export const MARKDOWN_CHUNKER_VERSION = 4;
+export const MARKDOWN_CHUNKER_VERSION = 3;
 
 const DELIMITERS: string[][] = [
   ['\n\n'],                          // L0: paragraphs
@@ -66,20 +48,8 @@ export interface ChunkOptions {
   chunkSize?: number;    // target words per chunk (default 300)
   chunkOverlap?: number; // overlap words (default 50)
   maxChars?: number;     // hard cap on any chunk's char length (default 6000)
-  /**
-   * v4: hard cap on any chunk's ESTIMATED embedding tokens (default 1500).
-   * Estimate = conservative per-char-class weights (see cjk.ts
-   * estimateEmbeddingTokens) — deliberately high, so the real tokenizer
-   * count stays below this value. Default leaves headroom for the
-   * contextual-retrieval wrapper (≤ ~630 chars) under a ~2,050-token
-   * per-request embedding server limit.
-   */
-  maxTokens?: number;
 }
 
-/** v4 default for ChunkOptions.maxTokens — see the field doc above. */
-export const DEFAULT_MAX_EST_TOKENS = 1500;
-
 export interface TextChunk {
   text: string;
   index: number;
@@ -103,7 +73,6 @@ export function chunkText(text: string, opts?: ChunkOptions): TextChunk[] {
   const chunkSize = opts?.chunkSize || 300;
   const chunkOverlap = opts?.chunkOverlap || 50;
   const maxChars = opts?.maxChars || 6000;
-  const maxTokens = opts?.maxTokens || DEFAULT_MAX_EST_TOKENS;
 
   if (!text || text.trim().length === 0) return [];
 
@@ -120,9 +89,8 @@ export function chunkText(text: string, opts?: ChunkOptions): TextChunk[] {
 
   const wordCount = countWords(stripped);
   if (wordCount <= chunkSize) {
-    // Single-chunk path: still apply the maxChars + maxTokens caps.
-    const capped = capByChars(stripped.trim(), maxChars)
-      .flatMap((t) => capByEstimatedTokens(t, maxTokens));
+    // Single-chunk path: still apply the maxChars cap.
+    const capped = capByChars(stripped.trim(), maxChars);
     return capped.map((t, i) => ({ text: t, index: i }));
   }
 
@@ -133,14 +101,9 @@ export function chunkText(text: string, opts?: ChunkOptions): TextChunk[] {
   // v0.32.7: hard char cap. Catches pathological CJK + whitespace-less text
   // that the word-level pipeline can't bound (a single Chinese paragraph can
   // exceed 8192 OpenAI embedding tokens at any word count).
-  // v4: estimated-token cap on top — the char cap alone passes token-dense
-  // content (URL soup at ~1.6 chars/token) that overflows strict embedding
-  // server limits.
   const capped: string[] = [];
   for (const chunk of withOverlap) {
-    for (const piece of capByChars(chunk.trim(), maxChars)) {
-      capped.push(...capByEstimatedTokens(piece, maxTokens));
-    }
+    capped.push(...capByChars(chunk.trim(), maxChars));
   }
   return capped.map((t, i) => ({ text: t, index: i }));
 }
@@ -169,68 +132,6 @@ function capByChars(text: string, maxChars: number): string[] {
   return out;
 }
 
-/**
- * How far back (in chars) the token cap looks for a friendly cut point
- * before falling back to a hard cut. 300 covers typical rollup/list line
- * lengths so forced splits land at line starts, not mid-URL.
- */
-const TOKEN_CAP_CUT_LOOKBACK = 300;
-
-/**
- * v4: hard-cap a chunk's ESTIMATED embedding tokens. Final safety pass —
- * runs after capByChars on every chunk, so no upstream miscounting
- * (whitespace-word fallback, overlap inflation, char-cap survivors) can
- * emit a chunk past `maxTokens`.
- *
- * Cut placement prefers, within the last TOKEN_CAP_CUT_LOOKBACK chars of
- * the window: a newline, then any whitespace, then a hard cut. This keeps
- * forced splits off mid-line/mid-URL positions for list-shaped content
- * and inside code fences. No overlap is added (pieces stay lossless
- * modulo the trims the char cap already applies).
- *
- * @internal exported for the code chunker (code.ts) and tests.
- */
-export function capByEstimatedTokens(text: string, maxTokens: number): string[] {
-  if (text.length === 0) return [];
-  if (estimateEmbeddingTokens(text) <= maxTokens) return [text];
-
-  const out: string[] = [];
-  let start = 0;
-  while (start < text.length) {
-    // Greedily extend the window until the next char would break the cap.
-    // Always take at least one char so the loop makes forward progress.
-    let est = 0;
-    let end = start;
-    while (end < text.length) {
-      const w = charEmbedTokenWeight(text.charCodeAt(end));
-      if (est + w > maxTokens && end > start) break;
-      est += w;
-      end++;
-    }
-
-    if (end < text.length) {
-      const windowStart = Math.max(start + 1, end - TOKEN_CAP_CUT_LOOKBACK);
-      let cut = text.lastIndexOf('\n', end - 1);
-      if (cut < windowStart) {
-        cut = -1;
-        for (let i = end - 1; i >= windowStart; i--) {
-          const code = text.charCodeAt(i);
-          if (code === 0x20 || (code >= 0x09 && code <= 0x0d)) {
-            cut = i;
-            break;
-          }
-        }
-      }
-      if (cut >= windowStart) end = cut + 1;
-    }
-
-    const slice = text.slice(start, end).trim();
-    if (slice.length > 0) out.push(slice);
-    start = end;
-  }
-  return out;
-}
-
 function recursiveSplit(text: string, level: number, target: number): string[] {
   if (level >= DELIMITERS.length) {
     // Level 4: split on whitespace
@@ -416,19 +317,7 @@ function extractTrailingContext(text: string, targetWords: number): string {
  * Delegated to src/core/cjk.ts so the slugify whitelist, expansion
  * detection, and PGLite keyword fallback all agree on what "CJK enough"
  * means.
- *
- * v4: floored at ceil(nonWhitespaceChars/6). The whitespace fallback
- * counts a 150-char URL as ONE word, so URL/phone/email-dense docs
- * (whose ASCII mass pushes CJK density below the 0.30 threshold) were
- * sized at a fraction of their real bulk and merged into 3-4K-char
- * chunks. The floor makes long whitespace-less runs count roughly
- * per-character while leaving normal Latin prose untouched (average
- * English word ≈ 5 chars < 6, so the whitespace count still wins).
- * Kept local to the chunker — search/expansion.ts keeps the original
- * countCJKAwareWords semantics for its query-length check.
  */
 function countWords(text: string): number {
-  const cjkAware = countCJKAwareWords(text);
-  const nonWhitespace = text.replace(/\s/g, '').length;
-  return Math.max(cjkAware, Math.ceil(nonWhitespace / 6));
+  return countCJKAwareWords(text);
 }

src/core/cjk.ts

@@ -65,64 +65,3 @@ export function countCJKAwareWords(s: string): number {
 export function escapeLikePattern(s: string): string {
   return s.replace(/\\/g, '\\\\').replace(/%/g, '\\%').replace(/_/g, '\\_');
 }
-
-/**
- * Conservative per-char-class embedding-token weights (markdown chunker v4).
- *
- * Why this exists: the chunker's "word" counting drastically UNDER-counts
- * whitespace-less ASCII runs (a 150-char URL = 1 whitespace word), so
- * word-based size targets can emit chunks that overflow an embedding
- * server's per-request token limit. Measured on a local Qwen3-embedding
- * llama-server stack:
- *   - URL/phone/email-dense text tokenizes at ~1.6 chars/token
- *   - base64-ish / minified blobs approach ~1.3 chars/token (worst case)
- *   - Korean prose tokenizes NO WORSE than 1 char/token in practice
- *
- * Weights are deliberately HIGH (tokens are overestimated) so any cap
- * based on this estimate is safe against real tokenizers:
- *   - CJK char        → 1.0 token  (real CJK prose is cheaper)
- *   - other non-space → 0.75 token (≈1.33 chars/token, covers base64)
- *   - whitespace      → 0.1 token  (mostly folds into neighbor tokens)
- */
-export const EMBED_TOKEN_WEIGHT_CJK = 1.0;
-export const EMBED_TOKEN_WEIGHT_OTHER = 0.75;
-export const EMBED_TOKEN_WEIGHT_WS = 0.1;
-
-/** BMP CJK check by UTF-16 code unit — same ranges as CJK_SLUG_CHARS. */
-export function isCJKCodeUnit(code: number): boolean {
-  return (
-    (code >= 0x4e00 && code <= 0x9fff) || // Han
-    (code >= 0x3040 && code <= 0x309f) || // Hiragana
-    (code >= 0x30a0 && code <= 0x30ff) || // Katakana
-    (code >= 0xac00 && code <= 0xd7af)    // Hangul Syllables
-  );
-}
-
-/**
- * Per-code-unit token weight. Unrecognized whitespace (exotic Unicode
- * spaces) intentionally falls into OTHER — that only overestimates.
- */
-export function charEmbedTokenWeight(code: number): number {
-  if (isCJKCodeUnit(code)) return EMBED_TOKEN_WEIGHT_CJK;
-  if (
-    code === 0x20 || (code >= 0x09 && code <= 0x0d) ||
-    code === 0xa0 || code === 0x3000
-  ) {
-    return EMBED_TOKEN_WEIGHT_WS;
-  }
-  return EMBED_TOKEN_WEIGHT_OTHER;
-}
-
-/**
- * Tokenizer-free embedding-token estimate (conservative overestimate).
- * See weight docs above. Astral chars count as 2 OTHER code units —
- * another overestimate, which is the safe direction.
- */
-export function estimateEmbeddingTokens(s: string): number {
-  if (s.length === 0) return 0;
-  let est = 0;
-  for (let i = 0; i < s.length; i++) {
-    est += charEmbedTokenWeight(s.charCodeAt(i));
-  }
-  return Math.ceil(est);
-}

src/core/connection-manager.ts

@@ -167,6 +167,25 @@ export function deriveDirectUrl(url: string): string | null {
   }
 }
 
+/**
+ * Error codes that mean "the direct host is unreachable from this network"
+ * (#1641). The auto-derived db.<ref>.supabase.co host is IPv6-only without
+ * the paid IPv4 add-on, so ENOTFOUND/ECONNREFUSED here is expected on
+ * IPv4-only networks — we fall back to the pooler instead of failing init.
+ */
+const NETWORK_UNREACHABLE_CODES = [
+  'ENOTFOUND', 'ECONNREFUSED', 'ENETUNREACH', 'EHOSTUNREACH',
+  'ETIMEDOUT', 'CONNECT_TIMEOUT',
+];
+
+/** True when err looks like a network-unreachable failure (not auth/SQL). */
+export function isNetworkUnreachableError(err: unknown): boolean {
+  const code = (err as { code?: unknown } | null)?.code;
+  if (typeof code === 'string' && NETWORK_UNREACHABLE_CODES.includes(code)) return true;
+  const msg = err instanceof Error ? err.message : String(err);
+  return NETWORK_UNREACHABLE_CODES.some(c => msg.includes(c));
+}
+
 /**
  * Read kill-switch state from env. Subordinate to parent manager's state
  * when present (A2 inheritance).
@@ -319,7 +338,30 @@ export class ConnectionManager {
         throw err;
       });
     }
-    const pool = await this._directInit;
+    let pool: Sql | null;
+    try {
+      pool = await this._directInit;
+    } catch (err) {
+      // #1641: the derived direct host (db.<ref>.supabase.co) is IPv6-only
+      // without Supabase's IPv4 add-on. On IPv4-only networks the direct
+      // pool can never connect — permanently fall back to the read pool
+      // (self-activating kill-switch) instead of failing init/migrations.
+      // Non-network errors (auth, SQL) still throw: they mean misconfig,
+      // not unreachability.
+      if (isNetworkUnreachableError(err)) {
+        const alreadyWarned = this._killSwitch;
+        this._killSwitch = true;
+        const msg = err instanceof Error ? err.message : String(err);
+        if (!alreadyWarned) console.error(
+          `gbrain: direct connection to ${this._directUrl ? this.hostOnly(this._directUrl) : 'unknown host'} unreachable (${msg}); ` +
+          'falling back to the pooler for DDL/bulk (long migrations may hit the pooler statement timeout). ' +
+          'Set GBRAIN_DIRECT_DATABASE_URL to a reachable direct URL (e.g. the Session pooler, port 5432) or enable the Supabase IPv4 add-on; ' +
+          'GBRAIN_DISABLE_DIRECT_POOL=1 silences this.',
+        );
+        return this.getReadPool();
+      }
+      throw err;
+    }
     if (!pool) {
       // Defensive — initDirectPool should have thrown.
       throw new Error('connection-manager: direct pool init returned null');
@@ -350,8 +392,9 @@ export class ConnectionManager {
       },
     };
     const t0 = Date.now();
+    let pool: Sql | null = null;
     try {
-      const pool = postgres(this._directUrl, opts);
+      pool = postgres(this._directUrl, opts);
       // Probe to validate connectivity early.
       await pool`SELECT 1`;
       logConnectionEvent({
@@ -362,6 +405,9 @@ export class ConnectionManager {
       });
       return pool;
     } catch (err) {
+      // Don't leak the failed pool's sockets/timers (#1641 fallback keeps
+      // the process running afterward).
+      if (pool) await endPoolBounded(pool);
       logConnectionEvent({
         pool: 'ddl',
         op: 'error',

test/chunker-version-gate.test.ts

@@ -15,22 +15,19 @@ import { describe, test, expect } from 'bun:test';
 import { CHUNKER_VERSION } from '../src/core/chunkers/code.ts';
 
 describe('Layer 12 — CHUNKER_VERSION constant', () => {
-  test('bumped to 5 for the estimated-token hard cap', () => {
+  test('bumped to 4 for Cathedral II', () => {
     // v3: v0.19.0 Chonkie parity (tokenizer + small-sibling merge).
     // v4: v0.20.0 Cathedral II (qualified names + parent scope + doc_comment
     //     + fence extraction + chunk-grain FTS). Folded into content_hash
     //     so any bump forces clean re-chunks on next sync.
-    // v5: estimated-token hard cap on AST-path chunks (capCodeChunks) so
-    //     un-subdividable giant nodes can't overflow strict embedding
-    //     server token limits.
-    expect(CHUNKER_VERSION).toBe(5);
+    expect(CHUNKER_VERSION).toBe(4);
   });
 
   test('is stable across imports (not recomputed at call time)', async () => {
     const a = (await import('../src/core/chunkers/code.ts')).CHUNKER_VERSION;
     const b = (await import('../src/core/chunkers/code.ts')).CHUNKER_VERSION;
     expect(a).toBe(b);
-    expect(a).toBe(5);
+    expect(a).toBe(4);
   });
 });
 

test/chunkers/code.test.ts

@@ -10,8 +10,8 @@ import { describe, test, expect } from 'bun:test';
 import { chunkCodeText, detectCodeLanguage, CHUNKER_VERSION } from '../../src/core/chunkers/code.ts';
 
 describe('CHUNKER_VERSION', () => {
-  test('v5: estimated-token hard cap on AST-path chunks', () => {
-    expect(CHUNKER_VERSION).toBe(5);
+  test('v0.20.0 Cathedral II Layer 12 bumped to 4', () => {
+    expect(CHUNKER_VERSION).toBe(4);
   });
 });
 

test/chunkers/recursive.test.ts

@@ -135,14 +135,13 @@ describe('Recursive Text Chunker', () => {
 });
 
 describe('CJK chunking (v0.32.7)', () => {
-  test('MARKDOWN_CHUNKER_VERSION is 4', async () => {
+  test('MARKDOWN_CHUNKER_VERSION is 3', async () => {
     // v0.40.3.0: bumped 2→3 to signal the post-upgrade reembed sweep that
-    // contextual retrieval wrapping is now applied at embed time.
-    // v4: estimated-token hard cap + whitespace-word undercount floor
-    // (URL-dense docs produced chunks past strict embedding server token
-    // limits). Boundary change → forces re-chunk for chunker_version < 4.
+    // contextual retrieval wrapping is now applied at embed time. Chunk
+    // boundaries themselves are unchanged; the bump forces re-embed for
+    // pages where chunker_version < 3.
     const mod = await import('../../src/core/chunkers/recursive.ts');
-    expect(mod.MARKDOWN_CHUNKER_VERSION).toBe(4);
+    expect(mod.MARKDOWN_CHUNKER_VERSION).toBe(3);
   });
 
   test('long pure-Chinese paragraph splits into multiple chunks', () => {

test/chunkers/token-cap.test.ts

@@ -1,195 +0,0 @@
-/**
- * Markdown chunker v4 / code chunker v5 — estimated-token hard cap
- * regression tests.
- *
- * Reproduces a field failure: a local llama-server embedding backend
- * (`-ub 2048`) crashes deterministically (trace/BPT trap → EOF at the
- * client) when a single chunk exceeds ~2,050 real tokens. Two content
- * shapes triggered it:
- *
- *   1. Korean docs carrying one long source URL per line.
- *      The URLs' ASCII mass pushes CJK density below 0.30, flipping
- *      countCJKAwareWords to whitespace counting, where a 150-char URL
- *      counts as ONE word → chunks ballooned to 3-4K chars ≈ 2,000+
- *      real tokens (URL soup tokenizes at ~1.6 chars/token).
- *
- *   2. Large JSON code blocks (~7K chars) that the word pipeline
- *      undercounts the same way (few whitespace tokens).
- *
- * The fix: every emitted chunk must satisfy
- *   estimateEmbeddingTokens(chunk) <= maxTokens (default 1500)
- * where the estimate deliberately OVERSTATES real tokenizer counts.
- */
-
-import { describe, test, expect } from 'bun:test';
-import { chunkText, capByEstimatedTokens, DEFAULT_MAX_EST_TOKENS } from '../../src/core/chunkers/recursive.ts';
-import { chunkCodeText } from '../../src/core/chunkers/code.ts';
-import { estimateEmbeddingTokens } from '../../src/core/cjk.ts';
-
-/** Synthesize the failing shape: Korean rollup lines each ending in a long Notion URL. */
-function urlDenseKoreanRollup(lines: number): string {
-  const out: string[] = ['# 링크가 줄마다 붙는 한국어 예시 문서', ''];
-  for (let i = 0; i < lines; i++) {
-    const hex32 = (i * 2654435761 >>> 0).toString(16).padStart(8, '0').repeat(4);
-    out.push(
-      `- **항목 ${i}**: 이 줄은 청커 동작 검증을 위한 의미 없는 한국어 예시 문장입니다 · 전화 000-0000-${String(1000 + i)} · ` +
-      `이메일 user${i}@example.com · 링크: https://docs.example.com/pages/${hex32}?v=abcdef0123456789&ref=sample`,
-    );
-  }
-  return out.join('\n');
-}
-
-/** Synthesize a large pretty-printed JSON block with CJK values. */
-function bigJsonBlock(targetChars: number): string {
-  const entries: string[] = [];
-  let i = 0;
-  let len = 0;
-  while (len < targetChars) {
-    const row =
-      `  "item_${i}": { "name": "예시-${i}", "url": "https://example.com/api/v2/items/${i}?token=abc${i}def", "qty": ${i % 100}, "memo": "한국어 값이 섞인 예시 데이터" }`;
-    entries.push(row);
-    len += row.length;
-    i++;
-  }
-  return `{\n${entries.join(',\n')}\n}`;
-}
-
-describe('v4 estimated-token cap — URL-dense Korean doc (field-failure shape)', () => {
-  test('every chunk stays under the estimated-token cap', () => {
-    const md = urlDenseKoreanRollup(60);
-    const chunks = chunkText(md);
-    expect(chunks.length).toBeGreaterThan(0);
-    for (const c of chunks) {
-      expect(estimateEmbeddingTokens(c.text)).toBeLessThanOrEqual(DEFAULT_MAX_EST_TOKENS);
-    }
-  });
-
-  test('no chunk reaches the measured 3K-char danger zone for URL soup', () => {
-    const md = urlDenseKoreanRollup(60);
-    const chunks = chunkText(md);
-    // 1500 est tokens at the OTHER weight (0.75/char) bounds chunks to
-    // ~2,000 chars for pure ASCII — well under the ~3,300 chars where
-    // URL-dense content crosses ~2,050 real tokens (1.6 chars/token).
-    for (const c of chunks) {
-      expect(c.text.length).toBeLessThanOrEqual(2600);
-    }
-  });
-
-  test('content is preserved (no lines dropped by the cap)', () => {
-    const md = urlDenseKoreanRollup(60);
-    const chunks = chunkText(md);
-    const joined = chunks.map((c) => c.text).join('\n');
-    // Spot-check first / middle / last rollup lines survive chunking.
-    for (const marker of ['항목 0', '항목 30', '항목 59']) {
-      expect(joined).toContain(marker);
-    }
-  });
-});
-
-describe('v4 estimated-token cap — large JSON blocks', () => {
-  test('7K-char pretty JSON through the prose path stays under the cap', () => {
-    const md = `설정 파일 원문 보존:\n\n\`\`\`\n${bigJsonBlock(7000)}\n\`\`\`\n`;
-    const chunks = chunkText(md);
-    expect(chunks.length).toBeGreaterThan(1);
-    for (const c of chunks) {
-      expect(estimateEmbeddingTokens(c.text)).toBeLessThanOrEqual(DEFAULT_MAX_EST_TOKENS);
-    }
-  });
-
-  test('7K-char minified JSON (single whitespace-less token) stays under the cap', () => {
-    const minified = bigJsonBlock(7000).replace(/\n\s*/g, '');
-    const chunks = chunkText(minified);
-    expect(chunks.length).toBeGreaterThan(1);
-    for (const c of chunks) {
-      expect(estimateEmbeddingTokens(c.text)).toBeLessThanOrEqual(DEFAULT_MAX_EST_TOKENS);
-    }
-  });
-
-  test('json fence via the code chunker stays under the cap (+header slack)', async () => {
-    const chunks = await chunkCodeText(bigJsonBlock(7000), 'fence.json');
-    expect(chunks.length).toBeGreaterThan(0);
-    for (const c of chunks) {
-      // buildChunk prepends a short "[JSON] fence.json:…" header AFTER the
-      // body-level cap; allow ~60 est tokens of header slack. Real-token
-      // safety margin (2,050 − overestimated 1,500) absorbs this easily.
-      expect(estimateEmbeddingTokens(c.text)).toBeLessThanOrEqual(DEFAULT_MAX_EST_TOKENS + 60);
-    }
-  });
-});
-
-describe('v4 word-count floor — behavior preserved for normal content', () => {
-  test('Latin prose chunking is unchanged by the floor (avg word < 6 chars)', () => {
-    const prose = Array.from({ length: 120 }, (_, i) =>
-      `This is sentence number ${i} and it talks about ordinary things in plain words.`,
-    ).join(' ');
-    const chunks = chunkText(prose);
-    // Historical behavior: ~1,560 whitespace words → multiple ~300-word chunks.
-    expect(chunks.length).toBeGreaterThan(3);
-    for (const c of chunks) {
-      const words = c.text.split(/\s+/).length;
-      expect(words).toBeLessThanOrEqual(300 * 1.5 + 50); // merge cap + overlap
-    }
-  });
-
-  test('Korean prose (CJK-dense, no URLs) never triggers the token cap', () => {
-    const prose = Array.from({ length: 80 }, (_, i) =>
-      `이 문장은 순수 한국어 산문의 청킹 동작을 확인하기 위한 ${i}번째 예시 문장입니다.`,
-    ).join(' ');
-    const chunks = chunkText(prose);
-    expect(chunks.length).toBeGreaterThan(1);
-    for (const c of chunks) {
-      // CJK-dense chunks are char-counted (≈450 max) — nowhere near 1500.
-      expect(estimateEmbeddingTokens(c.text)).toBeLessThanOrEqual(700);
-    }
-  });
-});
-
-describe('capByEstimatedTokens unit behavior', () => {
-  test('returns input unchanged when under the cap', () => {
-    expect(capByEstimatedTokens('short text', 1500)).toEqual(['short text']);
-    expect(capByEstimatedTokens('', 1500)).toEqual([]);
-  });
-
-  test('prefers newline cut points within the lookback window', () => {
-    const line = 'x'.repeat(100);
-    const text = Array.from({ length: 40 }, () => line).join('\n');
-    const pieces = capByEstimatedTokens(text, 1000);
-    expect(pieces.length).toBeGreaterThan(1);
-    for (const p of pieces) {
-      // Every piece should be whole lines (multiples of the 100-char line).
-      for (const l of p.split('\n')) {
-        expect(l).toBe(line);
-      }
-    }
-  });
-
-  test('makes forward progress on whitespace-less input (hard cut)', () => {
-    const blob = 'a'.repeat(10_000);
-    const pieces = capByEstimatedTokens(blob, 1000);
-    expect(pieces.length).toBeGreaterThan(1);
-    expect(pieces.join('')).toBe(blob);
-    for (const p of pieces) {
-      expect(estimateEmbeddingTokens(p)).toBeLessThanOrEqual(1000);
-    }
-  });
-});
-
-describe('estimateEmbeddingTokens — weight sanity', () => {
-  test('overestimates URL-dense ASCII (0.75/char ≥ measured ~0.63/char)', () => {
-    const url = 'https://docs.example.com/pages/a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4?v=abc&ref=sample';
-    const est = estimateEmbeddingTokens(url);
-    expect(est).toBeGreaterThanOrEqual(Math.floor(url.length * 0.7));
-  });
-
-  test('counts CJK at 1 token/char', () => {
-    expect(estimateEmbeddingTokens('가나다라마')).toBe(5);
-  });
-
-  test('whitespace is nearly free', () => {
-    expect(estimateEmbeddingTokens('   \n\t  ')).toBeLessThanOrEqual(1);
-  });
-
-  test('empty string is 0', () => {
-    expect(estimateEmbeddingTokens('')).toBe(0);
-  });
-});

test/connection-manager.serial.test.ts

@@ -3,6 +3,7 @@ import {
   isSupabasePoolerUrl,
   deriveDirectUrl,
   readKillSwitchEnv,
+  isNetworkUnreachableError,
   resolveDirectPoolSize,
   ConnectionManager,
   DEFAULT_DIRECT_POOL_SIZE,
@@ -238,3 +239,65 @@ describe('ConnectionManager — parent inheritance (A2)', () => {
     }
   });
 });
+
+describe('isNetworkUnreachableError (#1641)', () => {
+  test('classifies network codes as unreachable', () => {
+    for (const code of ['ENOTFOUND', 'ECONNREFUSED', 'ENETUNREACH', 'EHOSTUNREACH', 'ETIMEDOUT', 'CONNECT_TIMEOUT']) {
+      const err = Object.assign(new Error('connect failed'), { code });
+      expect(isNetworkUnreachableError(err)).toBe(true);
+    }
+  });
+
+  test('classifies by message when code absent', () => {
+    expect(isNetworkUnreachableError(new Error('getaddrinfo ENOTFOUND db.abc.supabase.co'))).toBe(true);
+  });
+
+  test('auth/SQL errors are NOT unreachable', () => {
+    expect(isNetworkUnreachableError(new Error('password authentication failed for user "postgres"'))).toBe(false);
+    expect(isNetworkUnreachableError(new Error('syntax error at or near "SELEC"'))).toBe(false);
+    expect(isNetworkUnreachableError(null)).toBe(false);
+  });
+});
+
+describe('ConnectionManager — direct-pool fallback on unreachable host (#1641)', () => {
+  let originalKillSwitch: string | undefined;
+  let originalError: typeof console.error;
+  let errLines: string[];
+  beforeEach(() => {
+    originalKillSwitch = process.env.GBRAIN_DISABLE_DIRECT_POOL;
+    delete process.env.GBRAIN_DISABLE_DIRECT_POOL;
+    originalError = console.error;
+    errLines = [];
+    console.error = (...args: unknown[]) => { errLines.push(args.join(' ')); };
+  });
+  afterEach(() => {
+    console.error = originalError;
+    if (originalKillSwitch === undefined) delete process.env.GBRAIN_DISABLE_DIRECT_POOL;
+    else process.env.GBRAIN_DISABLE_DIRECT_POOL = originalKillSwitch;
+  });
+
+  test('ddl() falls back to the read pool when the direct host is unreachable', async () => {
+    const cm = new ConnectionManager({
+      url: 'postgresql://postgres.abc:p@aws.pooler.supabase.com:6543/db',
+      // 127.0.0.1:9 (discard) → instant ECONNREFUSED, the IPv4-only-network shape.
+      directUrl: 'postgresql://postgres:p@127.0.0.1:9/db',
+    });
+    const fakeReadPool = {} as ReturnType<typeof ConnectionManager.prototype.read>;
+    cm.setReadPool(fakeReadPool);
+    expect(cm.isDualPoolActive()).toBe(true);
+
+    const pool = await cm.ddl(); // without the fix this throws ECONNREFUSED
+    expect(pool).toBe(fakeReadPool);
+    // Self-activating kill-switch: subsequent calls skip the direct pool.
+    expect(cm.isKillSwitchActive()).toBe(true);
+    expect(cm.isDualPoolActive()).toBe(false);
+    expect(cm.describeMode().mode).toBe('single (kill-switch)');
+    // One stderr line mentioning the power-user override.
+    const warning = errLines.filter(l => l.includes('GBRAIN_DIRECT_DATABASE_URL'));
+    expect(warning.length).toBe(1);
+
+    const again = await cm.ddl();
+    expect(again).toBe(fakeReadPool);
+    expect(errLines.filter(l => l.includes('GBRAIN_DIRECT_DATABASE_URL')).length).toBe(1);
+  }, 20000);
+});