From 627a32022585d774a22e15a151d783b8686d2de7 Mon Sep 17 00:00:00 2001
From: Mateusz <mateusz.karpow@guardian.co.uk>
Date: Tue, 11 Aug 2026 01:24:02 +0200
Subject: [PATCH] Quote plain phrases containing reserved chars, not just
 whitespace
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interpreter.ts's strFromExpr serialised a CqlStr (plain phrase) back to
a string using hasWhitespace() alone to decide whether to re-quote it.
Chip keys/values (strFromField) already used the more complete
shouldQuoteFieldValue() (whitespace OR reserved char: `:`, `(`, `)`,
`"`). The two should agree — an unquoted colon is exactly as ambiguous
in a plain phrase as in a chip value, since the scanner treats a bare
colon as chip syntax everywhere.

Symptom: a quoted phrase like "hello:world" loses its quotes the
moment queryChange reports it, then gets mis-parsed as a hello:world
chip the next time that text is read (e.g. the next keystroke, or just
focusing the input again after the value was set once).
---
 .changeset/gentle-moles-jump.md      |  5 +++++
 lib/cql/src/lang/interpreter.spec.ts | 27 +++++++++++++++++++++++++++
 lib/cql/src/lang/interpreter.ts      |  4 ++--
 3 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/gentle-moles-jump.md

diff --git a/.changeset/gentle-moles-jump.md b/.changeset/gentle-moles-jump.md
new file mode 100644
index 00000000..d13ff899
--- /dev/null
+++ b/.changeset/gentle-moles-jump.md
@@ -0,0 +1,5 @@
+---
+"@guardian/cql": patch
+---
+
+Fix `queryChange`'s serialised `queryStr` dropping quotes from a plain phrase containing a reserved character (`:`, `(`, `)`, or `"`) with no whitespace, e.g. `"hello:world"`. Previously only whitespace triggered re-quoting for plain phrases, while chip keys/values already correctly checked reserved characters too — the two now use the same predicate (`shouldQuoteFieldValue`). Without this fix, a quoted phrase containing a colon is silently corrupted into an unquoted string, which then gets mis-parsed as a `key:value` chip the next time it's read.
diff --git a/lib/cql/src/lang/interpreter.spec.ts b/lib/cql/src/lang/interpreter.spec.ts
index 93897519..bd7045e2 100644
--- a/lib/cql/src/lang/interpreter.spec.ts
+++ b/lib/cql/src/lang/interpreter.spec.ts
@@ -27,6 +27,33 @@ describe("interpreter", () => {
     expect(str).toBe(queryStr);
   });
 
+  it("should quote a plain string containing a reserved char (colon)", () => {
+    const queryStr = `"hello:world"`;
+    const query = parser(queryStr).queryAst!;
+
+    const str = cqlQueryStrFromQueryAst(query);
+
+    expect(str).toBe(queryStr);
+  });
+
+  it("should quote a plain string containing a reserved char (parens)", () => {
+    const queryStr = `"(parenthetical)"`;
+    const query = parser(queryStr).queryAst!;
+
+    const str = cqlQueryStrFromQueryAst(query);
+
+    expect(str).toBe(queryStr);
+  });
+
+  it("should not quote a plain string with no reserved chars or whitespace", () => {
+    const queryStr = `hello`;
+    const query = parser(queryStr).queryAst!;
+
+    const str = cqlQueryStrFromQueryAst(query);
+
+    expect(str).toBe(queryStr);
+  });
+
   it("should escape reserved characters in chip keys and values", () => {
     const queryStr = `key:"\\"value\\""`;
     const query = parser(queryStr).queryAst!;
diff --git a/lib/cql/src/lang/interpreter.ts b/lib/cql/src/lang/interpreter.ts
index 92fa1abd..bcc6070f 100644
--- a/lib/cql/src/lang/interpreter.ts
+++ b/lib/cql/src/lang/interpreter.ts
@@ -1,5 +1,5 @@
 import { CqlBinary, CqlExpr, CqlField, CqlQuery } from "./ast";
-import { hasWhitespace, shouldQuoteFieldValue } from "./utils";
+import { shouldQuoteFieldValue } from "./utils";
 
 export const cqlQueryStrFromQueryAst = (query: CqlQuery): string => {
   const { content } = query;
@@ -17,7 +17,7 @@ const strFromExpr = (queryExpr: CqlExpr): string | undefined => {
   const renderedContent = (() => {
     switch (content.type) {
       case "CqlStr":
-        return hasWhitespace(content.searchExpr)
+        return shouldQuoteFieldValue(content.searchExpr)
           ? `"${content.searchExpr}"`
           : content.searchExpr;
       case "CqlGroup":