diff --git a/docs/linking-sessions-to-request-logs.md b/docs/linking-sessions-to-request-logs.md
new file mode 100644
index 0000000..af480ab
--- /dev/null
+++ b/docs/linking-sessions-to-request-logs.md
@@ -0,0 +1,177 @@
+# Linking pi sessions to request/response logs
+
+When `requestResponseLogging` is enabled, the daemon records every proxied
+upstream call as two files that share one id:
+
+- `requests/<id>.json` — method, url, baseUrl, redacted headers, request body
+- `responses/<id>.jsonl` — one JSON event per line: `response_start`, `chunk`,
+  `end` / `error`
+
+The `id` is minted in `src/daemon/request-response-log-sink.ts` (`makeId()`):
+the request's arrival time with `:`/`.` swapped for `-`, plus 8 hex chars, e.g.
+`2026-09-30T09-22-35-288Z-60c8e8cf`. The request's `id` and the response's
+`requestLogId` are the same string, so **the request and response logs are
+paired by filename stem** and never need matching against each other.
+
+Separately, pi records its own transcript per working directory. The two are
+written by different processes, so the session has no log id and the logs have
+no session id. This document explains the two keys that recover the link
+exactly, and how to run the mapper on redtop.
+
+## TL;DR
+
+```bash
+# on redtop
+bun scripts/link-session-logs.ts <session.jsonl> /home/user/.routstrd/reqRes
+```
+
+Every assistant turn prints the response log it produced. The request log is
+the same stem under `requests/`.
+
+## Where the data lives
+
+| | redtop (`ssh redtop`) | default |
+| --- | --- | --- |
+| request/response logs | `/home/user/.routstrd/reqRes` | `~/.routstrd/request-response-logs` |
+| log root on disk | `requestResponseLogging.dir` in `~/.routstrd/config.json` | `REQUEST_RESPONSE_LOGS_DIR` (`src/utils/config.ts`) |
+| pi sessions | `/home/user/.pi/agent/sessions/--<cwd>--/*.jsonl` | `~/.pi/agent/sessions/…` |
+| pi provider config | `/home/user/.pi/agent/models.json` (`providers.routstr`) | `~/.pi/agent/models.json` |
+
+On redtop the log root is set explicitly:
+
+```jsonc
+// ~/.routstrd/config.json
+"requestResponseLogging": { "enabled": true, "dir": "/home/user/.routstrd/reqRes" }
+```
+
+pi reaches the daemon through the `routstr` provider that
+`routstrd clients add pi-agent` writes into `models.json`
+(`src/integrations/pi.ts`, `configPath: ~/.pi/agent/models.json`). So the
+sessions and the logs on redtop are two views of the *same* traffic.
+
+Logs are stored uncompressed on redtop (`requests/*.json`,
+`responses/*.jsonl`). Elsewhere they may be brotli-compressed (`.jsonl.br`);
+the mapper handles both.
+
+## The join keys
+
+### 1. `responseId` ⇄ response stream id (primary, exact)
+
+Each assistant message in a pi session stores the upstream response id:
+
+```jsonc
+// session .jsonl
+{ "type": "message",
+  "timestamp": "2026-09-30T09:22:36.852Z",
+  "message": { "role": "assistant", "provider": "routstr",
+               "responseId": "chatcmpl-b5e868d7b747dd8be5a2fbc0b1313507", … } }
+```
+
+The response log replays the raw upstream SSE stream inside its `chunk` events,
+so the same id appears verbatim:
+
+```jsonc
+// responses/<id>.jsonl
+{ "requestLogId": "2026-09-30T09-22-35-288Z-60c8e8cf", "type": "chunk",
+  "text": "data: {\"id\":\"chatcmpl-b5e868d7b747dd8be5a2fbc0b1313507\", …}\n\n" }
+```
+
+The id prefix depends on which upstream provider answered — `chatcmpl-…` for
+Venice, `gen-…` for OpenRouter — but it is always present and always identical
+to `responseId`. Match on `chunk.text`, never on the raw file: the SSE text is
+JSON-escaped in the log, so `grep '"id":"'` misses it.
+
+### 2. request ⇄ response (exact, by id)
+
+`requests/<id>.json` and `responses/<id>.jsonl` share the filename stem
+(`id` == `requestLogId`). A response hit therefore yields its request for free.
+
+### 3. trigger timestamp ≈ request timestamp (secondary)
+
+The request log's `timestamp` is when the daemon received the call, which is
+the instant pi fired it — within ~10–30 ms of the *triggering* session message
+(the user turn or tool result), and within a few ms of the assistant record's
+epoch-ms `message.timestamp`. Useful as a sanity check or fallback, but not
+needed once key 1 works.
+
+## Running the mapper
+
+The mapper is `scripts/link-session-logs.ts` (bun, no extra deps):
+
+```bash
+bun run link-logs -- <session.jsonl> [logsDir] [--all] [--json]
+```
+
+- `logsDir` defaults to `$ROUTSTRD_LOG_DIR`, else `~/.routstrd/request-response-logs`.
+- `--all` scans every response log instead of only the session's UTC day (use
+  when a session spans midnight or logs were rotated).
+- `--json` prints a machine-readable table with both the `requests/` and
+  `responses/` paths per turn.
+
+On redtop the script must exist in the redtop checkout. Copy it over now (or
+`git pull` once the change is pushed):
+
+```bash
+scp scripts/link-session-logs.ts \
+    redtop:~/projects/routstr_main/routstrd/scripts/
+```
+
+`bun` is on `PATH` in an interactive fish session on redtop (`~/.bun/bin`);
+from a non-interactive shell, add it explicitly:
+
+```bash
+ssh redtop 'export PATH=$HOME/.bun/bin:$PATH; \
+  bun ~/projects/routstr_main/routstrd/scripts/link-session-logs.ts \
+      ~/.pi/agent/sessions/--home-user-projects-routstr_main-routstr-core--/<session>.jsonl \
+      ~/.routstrd/reqRes'
+```
+
+To work from the Mac against redtop's logs, either run it there over SSH (as
+above) or pull the logs first:
+
+```bash
+rsync -a redtop:/home/user/.routstrd/reqRes/ ~/.routstrd/reqRes-redtop/
+bun scripts/link-session-logs.ts <session.jsonl> ~/.routstrd/reqRes-redtop
+```
+
+### Finding the session for a given directory
+
+pi slugs the message's `cwd` into the session directory name by dropping the
+leading `/` and replacing the rest with `-`, wrapped in `--`:
+
+```
+/home/user/projects/routstr_main/routstr-core
+  -> ~/.pi/agent/sessions/--home-user-projects-routstr_main-routstr-core--/
+```
+
+Pick the file you want inside that directory (or `ls -t … | head -1` for the
+latest).
+
+## Verified
+
+Against this repo's own history the link is 1:1 and exact:
+
+- `2026-09-30T09-21-41-962Z_01a0f19e…jsonl` → **12/12** assistant turns matched
+  (provider: Venice, `chatcmpl-…`).
+- `2026-09-15T19-49-27-933Z_01a0a69e…jsonl` → **8/8** (OpenRouter, `gen-…`).
+- `2026-08-16T10-51-25-080Z_01a00a32…jsonl` → 51 of 55 turns carry a
+  `responseId`; all 51 matched (compressed `.br` logs).
+- On redtop, `2026-10-01T07-55-38-825Z_01a0f676…jsonl` → **2/2**.
+
+## Caveats
+
+- **Retries and aborted calls leave orphan logs.** A single assistant turn can
+  produce more than one request/response pair (transient `scp`-style failures,
+  provider retries), and some logs belong to sessions outside the one you are
+  looking at. Drive the join from the session, never assume the counts match.
+- **No `responseId` = no exact link.** The key exists in modern pi session
+  files (see the `2026-06-*` / `2026-08-*` sessions above). If a session omits
+  it, fall back to the trigger-timestamp window.
+- **Don't match on the system/developer prompt.** The session stores it as
+  `sections` (preamble + project context); the request log stores it as one
+  flattened `developer` message. They are not byte-identical.
+- **Content can quote an id.** Tool output that happens to contain an id string
+  can make a stem look like it matches an unrelated turn. The mapper only reads
+  `chunk.text`, which is model output, keeping this rare.
+- **Logging may start mid-history.** If `requestResponseLogging` was enabled
+  after a session began, earlier turns simply have no logs.
diff --git a/package.json b/package.json
index 0a7948b..40af913 100644
--- a/package.json
+++ b/package.json
@@ -24,6 +24,7 @@
     "lint": "tsc --noEmit",
     "test": "bun test",
     "smoke": "scripts/smoke/chat-completions.sh",
+    "link-logs": "bun scripts/link-session-logs.ts",
     "build": "bun build src/index.ts --target=bun --outfile=dist/index.js --external better-sqlite3 && bun build src/daemon/index.ts --target=bun --outfile=dist/daemon/index.js --external better-sqlite3",
     "build:binary": "bun build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig src/index.ts --outfile=dist/routstrd",
     "prepublishOnly": "bun run build"
diff --git a/scripts/link-session-logs.ts b/scripts/link-session-logs.ts
new file mode 100644
index 0000000..db7be22
--- /dev/null
+++ b/scripts/link-session-logs.ts
@@ -0,0 +1,176 @@
+#!/usr/bin/env bun
+/**
+ * link-session-logs.ts — map a pi session transcript to the routstrd
+ * request/response logs it produced.
+ *
+ * When `requestResponseLogging` is enabled the daemon writes one
+ * `requests/<id>.json` and one `responses/<id>.jsonl` per proxied upstream
+ * call. A pi session (see `routstrd clients add pi-agent`) records the same
+ * calls in its own transcript, under `~/.pi/agent/sessions/<cwd-slug>/*.jsonl`.
+ *
+ * The two are written by different processes, so there is no session id on the
+ * log side and no log id on the session side — but each assistant message in
+ * the session stores the upstream response id (`message.responseId`), and that
+ * same id appears verbatim inside the response log's SSE chunks. The request
+ * and response logs then share one id (`requests/<id>.json` ↔
+ * `responses/<id>.jsonl`, `id` == `requestLogId`), so a response hit yields the
+ * request too.
+ *
+ * Usage:
+ *   bun scripts/link-session-logs.ts <session.jsonl> [logsDir] [--all] [--json]
+ *
+ *   logsDir   Request/response log root. Defaults to $ROUTSTRD_LOG_DIR, else
+ *             ~/.routstrd/request-response-logs. On redtop it is
+ *             /home/user/.routstrd/reqRes (see requestResponseLogging.dir).
+ *   --all     Scan every response log instead of only the session's UTC day
+ *             (slower; use when a session spans midnight or logs were rotated).
+ *   --json    Emit machine-readable JSON instead of a table.
+ */
+import { readFileSync, readdirSync, existsSync } from "node:fs";
+import { homedir } from "node:os";
+import { basename, join } from "node:path";
+import { brotliDecompressSync } from "node:zlib";
+
+const ID_RE = /"id"\s*:\s*"([^"]+)"/g;
+
+interface Turn {
+  /** ISO timestamp of the assistant message (also when the request fired). */
+  timestamp: string;
+  responseId?: string;
+  model?: string;
+}
+
+function readMaybeCompressed(path: string): string {
+  const buf = readFileSync(path);
+  if (!path.endsWith(".br")) return buf.toString("utf8");
+  try {
+    return brotliDecompressSync(buf).toString("utf8");
+  } catch {
+    return buf.toString("utf8");
+  }
+}
+
+/** Upstream generation ids emitted inside a response log's SSE chunks. */
+function responseIds(path: string): Set<string> {
+  const ids = new Set<string>();
+  for (const line of readMaybeCompressed(path).split("\n")) {
+    if (!line.trim()) continue;
+    let event: { type?: string; text?: string };
+    try {
+      event = JSON.parse(line);
+    } catch {
+      continue;
+    }
+    if (event.type !== "chunk" || typeof event.text !== "string") continue;
+    for (const match of event.text.matchAll(ID_RE)) ids.add(match[1]!);
+  }
+  return ids;
+}
+
+function assistantTurns(sessionPath: string): Turn[] {
+  const turns: Turn[] = [];
+  for (const line of readFileSync(sessionPath, "utf8").split("\n")) {
+    if (!line.trim()) continue;
+    let record: { type?: string; timestamp?: string; message?: { role?: string; responseId?: string; responseModel?: string } };
+    try {
+      record = JSON.parse(line);
+    } catch {
+      continue;
+    }
+    if (record.type !== "message" || record.message?.role !== "assistant") continue;
+    turns.push({
+      timestamp: record.timestamp ?? "",
+      responseId: record.message.responseId,
+      model: record.message.responseModel,
+    });
+  }
+  return turns;
+}
+
+/** Strip the `.jsonl` / `.jsonl.br` suffix to recover the log id (stem). */
+function stemOf(file: string): string {
+  return file.replace(/\.jsonl(\.br)?$/, "");
+}
+
+function main(): void {
+  const args = process.argv.slice(2);
+  const flags = new Set(args.filter((a) => a.startsWith("--")));
+  const positional = args.filter((a) => !a.startsWith("--"));
+  const [sessionPath, logsArg] = positional;
+
+  if (!sessionPath) {
+    console.error("usage: bun scripts/link-session-logs.ts <session.jsonl> [logsDir] [--all] [--json]");
+    process.exit(2);
+  }
+
+  const logsDir =
+    logsArg || process.env.ROUTSTRD_LOG_DIR || join(homedir(), ".routstrd", "request-response-logs");
+  const responsesDir = join(logsDir, "responses");
+  const requestsDir = join(logsDir, "requests");
+  if (!existsSync(responsesDir)) {
+    console.error(`no responses directory at ${responsesDir}`);
+    process.exit(2);
+  }
+
+  const day = basename(sessionPath).slice(0, 10); // YYYY-MM-DD
+  const candidates = readdirSync(responsesDir).filter(
+    (file) => file.endsWith(".jsonl") || file.endsWith(".jsonl.br"),
+  );
+  const scanned = flags.has("--all") ? candidates : candidates.filter((file) => file.startsWith(day));
+
+  // responseId -> response log stem(s). Usually one; retries or quoted ids can
+  // make a stem appear more than once, so keep every hit.
+  const byResponseId = new Map<string, string[]>();
+  for (const file of scanned) {
+    const stem = stemOf(file);
+    for (const id of responseIds(join(responsesDir, file))) {
+      const hits = byResponseId.get(id) ?? [];
+      if (!hits.includes(stem)) hits.push(stem);
+      byResponseId.set(id, hits);
+    }
+  }
+
+  const turns = assistantTurns(sessionPath);
+  const rows = turns.map((turn) => {
+    const stems = turn.responseId ? (byResponseId.get(turn.responseId) ?? []) : [];
+    return {
+      timestamp: turn.timestamp,
+      responseId: turn.responseId ?? null,
+      model: turn.model ?? null,
+      responseLogs: stems.map((stem) => join(responsesDir, `${stem}.jsonl`)),
+      requestLogs: stems.map((stem) => {
+        const plain = join(requestsDir, `${stem}.json`);
+        return existsSync(plain) ? plain : join(requestsDir, `${stem}.json.br`);
+      }),
+      matched: stems.length > 0,
+    };
+  });
+
+  if (flags.has("--json")) {
+    console.log(JSON.stringify(rows, null, 2));
+    return;
+  }
+
+  const matched = rows.filter((r) => r.matched).length;
+  console.log(`session : ${sessionPath}`);
+  console.log(`logs    : ${logsDir}`);
+  console.log(`scanned : ${scanned.length} response log(s)${flags.has("--all") ? " (all)" : ` for ${day}`}`);
+  console.log(`turns   : ${rows.length} assistant message(s), ${matched} matched\n`);
+
+  const width = Math.max(...rows.map((r) => (r.responseId ?? "—").length), 10);
+  for (const row of rows) {
+    const id = (row.responseId ?? "—").padEnd(width);
+    const hit = row.matched ? row.responseLogs[0]!.replace(`${logsDir}/`, "") : "NO MATCH";
+    console.log(`  ${row.timestamp}  ${id}  ${hit}`);
+  }
+
+  const unmatched = rows.filter((r) => !r.matched);
+  if (unmatched.length > 0) {
+    console.log(
+      `\n${unmatched.length} unmatched turn(s). If the session spans midnight or the logs were` +
+        ` rotated, re-run with --all. Pre-responseId pi versions cannot be matched this way.`,
+    );
+  }
+}
+
+main();