fix(plugins): flush on exit regardless of backoff, and prefer the backlog over new events

Findings from an independent review of this branch.

The exit-time flush was gated by its own cooldown. beforeExit called the same
flush() that opens with a retryNotBefore check, so after any failed delivery a
process exiting inside the 2s to 60s window sent nothing and the queue died with
it. That is precisely the loss this branch exists to stop, and timer.unref makes
beforeExit often the only remaining chance. flush(force) now skips the cooldown
and beforeExit passes it.

Overflow kept the newest and evicted the batch being retried, which threw away
exactly the events the retry exists to save. Both the failure path and capture()
now keep the backlog and drop the new event instead, matching Python's record(),
which refuses new events once the spool is full.

That change needs a bound, so delivery now gives up after five attempts, as the
Python core does. Without one a payload the server will never accept would be
retried for the whole session and, with the backlog now preferred, would hold the
queue against everything behind it.

Events carry a capture-time timestamp. They now sit through backoff and across
an entire outage, so without one PostHog records them at whatever moment delivery
happened to succeed. It also matters for the uuid dedupe, whose key includes the
event date.

openclaw wiped a resolved account on any capture without an apiKey: the
fingerprint comparison was `undefined === ""`, so a keyless call looked like a key
change. Guarded on a real key being present. Masked today because every call site
supplies one, which is why only a test found it.

Two smaller ones. opencode's PostHog source was "plugin", which named no
particular plugin and matched no vocabulary; it is now OPENCODE_PLUGIN like every
other surface, and a saved insight filtering source = "plugin" needs repointing.
And an em dash in opencode's published description had been rewritten to a —
escape by my own json.dumps when adding the test script; restored.

One openclaw test asserted only not.toThrow() under a name claiming it checked
the identity, and under the fingerprint gate the path it exercised no longer uses
the email at all. It now pins the real condition.

core 35, openclaw 432, opencode 35, pi-agent 89, deepseek 47. The wire e2e still
passes 9 of 9 against a real local server, and the identity e2e 7 of 7.

Claude-Session: https://claude.ai/code/session_01C7tEmH86HAr7GoAAKCEHZb

integrations/opencode-plugin/package.json

@@ -2,7 +2,7 @@
   "name": "@mem0/opencode-plugin",
   "version": "0.3.0",
   "type": "module",
-  "description": "Mem0 persistent memory plugin for OpenCode \u2014 add, search, and manage memories across sessions",
+  "description": "Mem0 persistent memory plugin for OpenCode — add, search, and manage memories across sessions",
   "main": "dist/index.js",
   "types": "index.d.ts",
   "exports": {

integrations/opencode-plugin/telemetry.test.ts

@@ -15,7 +15,10 @@ describe("opencode telemetry", () => {
     expect(payload).not.toBeNull();
     const props = payload!.properties as Record<string, unknown>;
     expect(payload!.event).toBe("plugin.session_start");
-    expect(props.source).toBe("plugin");
+    // Was "plugin", which named no particular plugin and matched no vocabulary.
+    // Now shaped like every other surface. Any saved PostHog insight filtering
+    // source = "plugin" needs repointing; historical data is untouched.
+    expect(props.source).toBe("OPENCODE_PLUGIN");
     expect(props.platform).toBe("opencode");
     expect(props.memory_count).toBe(5);
     expect(props.$process_person_profile).toBe(false);
@@ -32,7 +35,7 @@ describe("opencode telemetry", () => {
     const props = buildEvent("x", { platform: "HACK", source: "HACK" }, KEY)!
       .properties as Record<string, unknown>;
     expect(props.platform).toBe("opencode");
-    expect(props.source).toBe("plugin");
+    expect(props.source).toBe("OPENCODE_PLUGIN");
   });
 
   test("returns null without an API key (no anonymous events)", () => {

integrations/opencode-plugin/telemetry.ts

@@ -25,7 +25,9 @@ const PLUGIN_VERSION = (() => {
 let currentDistinctId = "";
 const telemetry = createTelemetry({
   host: "opencode",
-  source: "plugin",
+  // Shaped like the platform's EventSource values, as every other surface is.
+  // "plugin" said nothing about which plugin and matched no vocabulary.
+  source: "OPENCODE_PLUGIN",
   version: PLUGIN_VERSION,
   distinctId: () => currentDistinctId,
   eventName: (event) => `plugin.${event}`,