fix(coding-agent): bridge isContextOverflow in legacy pi-ai shim

Upstream @earendil-works/pi-ai re-exported isContextOverflow from its
package root, but omp's @oh-my-pi/pi-ai barrel forwards only
./error/rate-limit, so the shim's `export * from "@oh-my-pi/pi-ai"` left
it off the surface. Plugins importing it (pi-blackhole) tripped Bun's
static named-export check during validation, both on disk and through the
omp-legacy-pi-bundled: virtual namespace.

Audited the upstream root surface rather than fix one symbol at a time:
of its runtime exports only isContextOverflow (now under
@oh-my-pi/pi-ai/error) and parseJsonWithRepair/parseStreamingJson/
repairJson (relocated to @oh-my-pi/pi-utils) still exist in omp. Bridge
exactly that set through the shim and pin it with a regression test that
exercises each helper's behavior.

Fixes #6859

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed `omp plugin install` of legacy pi extensions failing Bun's static named-export validation on `isContextOverflow` (e.g. `pi-blackhole`). The `@oh-my-pi/pi-ai` root barrel dropped upstream `@earendil-works/pi-ai`'s root re-export, so `legacy-pi-ai-shim.ts` (which backs both on-disk and `omp-legacy-pi-bundled:` virtual resolution) never surfaced it. The shim now bridges every upstream-root runtime symbol that still exists in omp — `isContextOverflow` (from `@oh-my-pi/pi-ai/error`) and `parseJsonWithRepair`/`parseStreamingJson`/`repairJson` (from `@oh-my-pi/pi-utils`) ([#6859](https://github.com/can1357/oh-my-pi/issues/6859)).
+
 ## [17.1.7] - 2026-07-27
 
 ### Fixed

packages/coding-agent/src/extensibility/legacy-pi-ai-shim.ts

@@ -93,3 +93,21 @@ export * from "@oh-my-pi/pi-ai";
 export { calculateCost, getBundledModel, getBundledModels, getBundledProviders, modelsAreEqual, Type };
 export const getModel = getBundledModel;
 export const getModels = getBundledModels;
+
+/**
+ * Compatibility re-exports for runtime helpers that upstream
+ * `@earendil-works/pi-ai` exposed from its package root but omp's
+ * `@oh-my-pi/pi-ai` barrel no longer forwards. Each symbol still exists in the
+ * host graph — only its root re-export was dropped — so bridging it here keeps
+ * legacy extensions importing it from the pi-ai root resolving through Bun's
+ * static named-export check (e.g. `omp plugin install pi-blackhole`).
+ *
+ * This is the full set derived from an audit of the upstream root surface: the
+ * error-classification predicate `isContextOverflow` (now under
+ * `@oh-my-pi/pi-ai/error`) and the JSON-repair helpers that omp relocated to
+ * `@oh-my-pi/pi-utils`. Upstream root symbols with no omp equivalent are
+ * intentionally not shimmed — the package has diverged and there is nothing to
+ * forward.
+ */
+export { isContextOverflow } from "@oh-my-pi/pi-ai/error";
+export { parseJsonWithRepair, parseStreamingJson, repairJson } from "@oh-my-pi/pi-utils";

packages/coding-agent/test/extensibility/legacy-pi-ai-root-exports.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from "bun:test";
+import type { AssistantMessage } from "@oh-my-pi/pi-ai";
+import {
+	isContextOverflow,
+	parseJsonWithRepair,
+	parseStreamingJson,
+	repairJson,
+} from "@oh-my-pi/pi-coding-agent/extensibility/legacy-pi-ai-shim";
+
+// Issue #6859: pi extensions import runtime helpers from the `@earendil-works/pi-ai`
+// (aliased to `@oh-my-pi/pi-ai`) package root that omp's barrel no longer forwards.
+// `isContextOverflow` moved under `@oh-my-pi/pi-ai/error` and the JSON-repair
+// helpers moved to `@oh-my-pi/pi-utils`, so `export * from "@oh-my-pi/pi-ai"` left
+// them off the shim surface and a named import tripped Bun's static
+// "No matching export" check during plugin validation (e.g.
+// `omp plugin install pi-blackhole`). This pins the bridged root surface so it
+// cannot silently regress the way #6583 / #6648 did one symbol at a time.
+function createErrorMessage(errorMessage: string): AssistantMessage {
+	return {
+		role: "assistant",
+		content: [{ type: "text", text: "" }],
+		api: "anthropic-messages",
+		provider: "anthropic",
+		model: "claude-sonnet-4-5",
+		usage: {
+			input: 0,
+			output: 0,
+			cacheRead: 0,
+			cacheWrite: 0,
+			totalTokens: 0,
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+		},
+		stopReason: "error",
+		errorMessage,
+		timestamp: Date.now(),
+	};
+}
+
+describe("legacy pi-ai shim root exports", () => {
+	it("re-exports isContextOverflow with its classification behavior", () => {
+		expect(typeof isContextOverflow).toBe("function");
+		expect(isContextOverflow(createErrorMessage("prompt is too long: 300000 tokens > 200000 maximum"))).toBe(true);
+		expect(isContextOverflow(createErrorMessage("400 Bad Request: invalid API key"))).toBe(false);
+	});
+
+	it("re-exports the JSON-repair helpers that upstream exposed at the pi-ai root", () => {
+		// repairJson escapes a raw control char inside a string so JSON.parse stops throwing.
+		const broken = `{"a": "b${String.fromCharCode(1)}c"}`;
+		expect(() => JSON.parse(broken)).toThrow();
+		expect(JSON.parse(repairJson(broken))).toEqual({ a: "b\u0001c" });
+		// parseJsonWithRepair tolerates trailing commas / unquoted keys.
+		expect(parseJsonWithRepair<{ a: number }>("{a: 1,}")).toEqual({ a: 1 });
+		// parseStreamingJson completes a truncated object at the streaming edge.
+		expect(parseStreamingJson<{ a: number }>('{"a": 1')).toEqual({ a: 1 });
+	});
+});