fix(web): resolve the replay tool from the draft, and say why a draft is stuck

Copilot's ninth pass, three comments, two of them consequences of round 8.

- The coercion check resolved the tool from the *entry's* name while the modal
  lets `name` be edited, so retargeting an `echo` replay at `add` validated
  against `echo`. The modal now takes the whole tool list and resolves from the
  draft's current name, which is the one the dispatch will look up.

- `IMPRECISE_INTEGER_ERROR` (was `ROUNDED_INTEGER_ERROR`) no longer names the
  safe-integer range, because the range is not the rule: a whole number past
  ±(2^53 − 1) that is exactly representable round-trips and is accepted. It
  talks about exact representability instead, and its doc links the helper that
  actually exists.

- `SchemaJsonField` carries the parser's reason instead of flattening every
  case to "Not valid JSON", which misdiagnosed a document that parses fine and
  holds a number this client cannot send — leaving the user reading about
  syntax while looking at syntactically fine JSON.

The last one had a bug the gate caught rather than the tests: empty text is not
a *problem*, so routing the value through the reason check let `JSON.parse("")`
throw out of the change handler. It surfaced as five unhandled errors across
four suites with every assertion still green, which is why `npm run ci` and not
`npm run test` is the gate. Excluded explicitly, with a regression test.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UL9retfvAXRgvi6EWk4SY4
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/components/groups/EditReplayModal/EditReplayModal.test.tsx

@@ -2,8 +2,23 @@ import { describe, it, expect, vi } from "vitest";
 import userEvent from "@testing-library/user-event";
 import { renderWithMantine, screen } from "../../../test/renderWithMantine";
 import { getAceText, setAceText } from "../../../test/aceEditor";
+import type { Tool } from "@modelcontextprotocol/client";
 import { EditReplayModal } from "./EditReplayModal";
 
+const TOOLS: Tool[] = [
+  {
+    name: "echo",
+    inputSchema: {
+      type: "object",
+      properties: { message: { type: "string" } },
+    },
+  },
+  {
+    name: "add",
+    inputSchema: { type: "object", properties: { count: { type: "number" } } },
+  },
+];
+
 const baseProps = {
   opened: true,
   method: "tools/call",
@@ -204,7 +219,7 @@ describe("EditReplayModal", () => {
     await setAceText('{"name":"echo","arguments":{"id":9007199254740993}}');
     expect(screen.getByRole("button", { name: "Send" })).toBeDisabled();
     expect(
-      screen.getByText(/A whole number written out in full must be within/),
+      screen.getByText(/cannot be represented exactly/),
     ).toBeInTheDocument();
   });
 
@@ -217,6 +232,39 @@ describe("EditReplayModal", () => {
     ).toBeInTheDocument();
   });
 
+  // `callTool` coerces string arguments to the type the schema declares, so
+  // `"2"` against a numeric field is sent as `2`.
+  it("disables Send for a tool argument the schema would coerce", async () => {
+    renderWithMantine(
+      <EditReplayModal {...baseProps} method="tools/call" tools={TOOLS} />,
+    );
+    await setAceText('{"name":"add","arguments":{"count":"2"}}');
+    expect(screen.getByRole("button", { name: "Send" })).toBeDisabled();
+    expect(screen.getByText(/`count` would be converted/)).toBeInTheDocument();
+  });
+
+  // `name` is editable, so the schema to validate against is whichever tool the
+  // draft *now* names — not the one the entry happened to call.
+  it("re-validates against the tool the draft retargets to", async () => {
+    renderWithMantine(
+      <EditReplayModal
+        {...baseProps}
+        method="tools/call"
+        params={{ name: "echo", arguments: { message: "hi" } }}
+        tools={TOOLS}
+      />,
+    );
+    expect(screen.getByRole("button", { name: "Send" })).not.toBeDisabled();
+
+    // Retargeted at `add`, whose `count` is a number — the string would coerce.
+    await setAceText('{"name":"add","arguments":{"count":"2"}}');
+    expect(screen.getByRole("button", { name: "Send" })).toBeDisabled();
+
+    // And back: `echo`'s `message` is a string, so nothing is converted.
+    await setAceText('{"name":"echo","arguments":{"message":"2"}}');
+    expect(screen.getByRole("button", { name: "Send" })).not.toBeDisabled();
+  });
+
   it("closes without sending when cancelled", async () => {
     const user = userEvent.setup();
     const onSend = vi.fn();