fix(pylon): adopt upstream protocol fixture repair

Merge the exact repair from PrimeIntellect-ai#1886 after the upstream main merge regressed protocol fixtures.

Author: pylon-upstream-sync[bot]

.pylon/features.yaml

@@ -133,3 +133,19 @@ decisions:
     revisit_when:
       - Prime adopts deterministic catalog fixtures or repo-owned structural invariants.
       - Prime stops regenerating vendor pricing before tests and releases.
+
+  kernel-protocol-test-fixtures:
+    area: runtime-reliability
+    state: adopted-ahead-of-upstream
+    owner: upstream
+    decision: adopt
+    pylon_refs:
+      - https://github.com/pylon-code/prime-agent/issues/4
+      - https://github.com/pylon-code/prime-agent/pull/5
+    upstream_refs:
+      - https://github.com/PrimeIntellect-ai/prime-agent/pull/1839
+      - https://github.com/PrimeIntellect-ai/prime-agent/pull/1886
+    fork_change: exact-upstream-pr-1886
+    upstream_support: "Prime PR #1886 repairs protocol fixtures regressed by the #1839 merge commit, but is not yet on main."
+    revisit_when:
+      - "Prime merges PR #1886 and the exact fix reaches the mirrored main branch."

.pylon/upstream-review.md

@@ -30,5 +30,7 @@ This ledger records Prime upstream evidence and the decision taken for each over
 - Reviewed Prime PRs #1878, #1876, #1877, and #1633 plus `generate-models.ts`, the generated model catalog, and the affected model tests. PR #1878 deliberately kept live catalog generation and refreshed Kimi K3 Prime Inference pricing. Prime closed the deterministic-CI and fixture-test proposals in #1876 and #1877; scheduled catalog refresh PR #1633 remains open.
 - `prime-inference-catalog-capabilities`: **hybridize**. Adopt Prime's current catalog and generator changes, but retain Pylon's route-scoped live-pricing invariants instead of pinning vendor-owned numeric prices that can drift independently before tests.
 - Reviewed the remaining upstream PRs in the range (#1841, #1846, #1849, #1852, #1853, #1835, #1838, #1861, #1836, and #1839). They apply without conflict and do not supersede landed Pylon fork behavior. Existing lifecycle decisions remain unchanged.
-- Validation: the focused Prime Inference catalog test passed all 12 cases; `npm run check` passed Biome over 937 files, the TypeScript check, installer rendering, and the browser smoke check; `git diff --check` passed.
+- Post-merge CI exposed an upstream-only regression: Prime main run `33186265648` and Pylon PR #5 both failed 23 kernel tests because the #1839 merge commit retained protocol 2 in fake runtimes while production requires protocol 3.
+- `kernel-protocol-test-fixtures`: **adopt** the exact three-line repair from open Prime PR #1886 at `a97f6995d39f2cccbd33123ab246f9786fc8ac13`. Preserve that upstream commit as a merge parent rather than creating Pylon-specific behavior.
+- Validation: the focused Prime Inference catalog test passed all 12 cases; the two protocol fixture suites passed all 39 cases; `npm run check` passed Biome over 937 files, the TypeScript check, installer rendering, and the browser smoke check; `git diff --check` passed.
 - Revisit when Prime adopts deterministic catalog fixtures or repo-owned structural invariants, or stops regenerating vendor pricing before tests and releases.

packages/coding-agent/test/ipython-provisioner.test.ts

@@ -73,7 +73,7 @@ function writeFakeReplRuntime(markerPath: string): string {
 const fs = require("node:fs");
 const readline = require("node:readline");
 const emit = (event) => process.stdout.write(JSON.stringify(event) + "\\n");
-emit({ event: "ready", protocol: 2, python: process.version });
+emit({ event: "ready", protocol: 3, python: process.version });
 const input = readline.createInterface({ input: process.stdin });
 input.on("line", (line) => {
 	const request = JSON.parse(line);

packages/coding-agent/test/repl-kernel-protocol-corruption.test.ts

@@ -32,10 +32,10 @@ if (fs.existsSync(process.env.FAKE_REPL_CORRUPT_BOOT)) {
   process.stdout.write("BROKEN-BOOT\\n");
 } else if (fs.existsSync(process.env.FAKE_REPL_READY_WITH_GARBAGE)) {
   process.stdout.write(
-    JSON.stringify({ event: "ready", protocol: 2, python: process.version }) + "\\nBROKEN-WITH-READY\\n",
+    JSON.stringify({ event: "ready", protocol: 3, python: process.version }) + "\\nBROKEN-WITH-READY\\n",
   );
 } else if (!(count > 1 && fs.existsSync(process.env.FAKE_REPL_DELAY_READY))) {
-  emit({ event: "ready", protocol: 2, python: process.version });
+  emit({ event: "ready", protocol: 3, python: process.version });
 }
 const input = readline.createInterface({ input: process.stdin });
 input.on("line", (line) => {