diff --git a/packages/agents/src/capture-event/cli.ts b/packages/agents/src/capture-event/cli.ts
index a855b520..2792de9c 100644
--- a/packages/agents/src/capture-event/cli.ts
+++ b/packages/agents/src/capture-event/cli.ts
@@ -14,6 +14,8 @@ import { ulid } from 'ulid';
 
 import { formatUtcTimestamp } from '../kb-shared/note-helpers.ts';
 import { resolveStoreByName } from '../kb-shared/resolve-store-by-name.ts';
+import { parseTagList } from '../kb-shared/tag-helpers.ts';
+import { readAll } from '../lib/stream-helpers.ts';
 import { isEnoent } from '../lib/type-guards.ts';
 import { prepareEvent } from './prepare-event.ts';
 import type { CaptureContext, CaptureResult, ParsedArgs } from './types.ts';
@@ -211,14 +213,6 @@ function matchValueFlag(arg: string): { key: ValueFlag; inlineValue: string | nu
   return null;
 }
 
-/** Splits a comma-separated tag string into individual tags, dropping empties and trimming whitespace. */
-function parseTagList(value: string): string[] {
-  return value
-    .split(',')
-    .map((tag) => tag.trim())
-    .filter((tag) => tag.length > 0);
-}
-
 /**
  * Resolves the `owner/name` git remote at `cwd`, best-effort. Prefers the `origin` remote and falls back to the first
  * listed remote when `origin` is absent. Both SSH (`git@host:owner/name.git`) and HTTPS (`https://host/owner/name.git`)
@@ -261,7 +255,11 @@ async function resolveRemoteUrl(cwd: string): Promise<string | undefined> {
   }
 }
 
-/** Normalizes an SSH or HTTPS git remote URL to `owner/name`, or `undefined` when it cannot be parsed. */
+/**
+ * Normalizes an SSH or HTTPS git remote URL to `owner/name`, or `undefined` when it cannot be parsed.
+ *
+ * @internal - Exported to allow testing.
+ */
 export function normalizeRemoteUrl(url: string): string | undefined {
   const withoutSuffix = url.replace(/\.git$/, '');
 
@@ -287,16 +285,4 @@ function takeOwnerName(path: string): string | undefined {
   return segments.slice(-2).join('/');
 }
 
-/** Reads a readable stream to completion as a UTF-8 string. */
-async function readAll(stream: Readable): Promise<string> {
-  const chunks: Buffer[] = [];
-  for await (const chunk of stream) {
-    if (!Buffer.isBuffer(chunk)) {
-      throw new TypeError('readAll: expected Buffer chunks (stream must be in binary mode)');
-    }
-    chunks.push(chunk);
-  }
-  return Buffer.concat(chunks).toString('utf8');
-}
-
 // endregion | Helpers
diff --git a/packages/agents/src/kb-add/cli.ts b/packages/agents/src/kb-add/cli.ts
index 5ce90a52..d1896e7b 100644
--- a/packages/agents/src/kb-add/cli.ts
+++ b/packages/agents/src/kb-add/cli.ts
@@ -11,6 +11,8 @@ import { loadSchema } from '@codeassembly/kb/schema';
 import { loadAliases } from '@codeassembly/kb/tags';
 
 import { resolveWritableKb } from '../kb-shared/resolve-writable-kb.ts';
+import { parseTagList } from '../kb-shared/tag-helpers.ts';
+import { readAll } from '../lib/stream-helpers.ts';
 import { prepareNote } from './prepare-note.ts';
 import type { AddResult, ParsedArgs } from './types.ts';
 import { writeNote } from './write-note.ts';
@@ -251,27 +253,4 @@ async function loadAliasesWithWarning(input: { kbRoot: KbRoot }): Promise<AliasM
   }
 }
 
-/** Splits a comma-separated tag string into individual tags, dropping empties and trimming whitespace. */
-function parseTagList(value: string): string[] {
-  return value
-    .split(',')
-    .map((tag) => tag.trim())
-    .filter((tag) => tag.length > 0);
-}
-
-/**
- * Reads a readable stream to completion as a UTF-8 string. Callers pass `process.stdin` (binary mode) or a
- * `Readable.from([Buffer])`, both of which emit `Buffer` chunks.
- */
-async function readAll(stream: Readable): Promise<string> {
-  const chunks: Buffer[] = [];
-  for await (const chunk of stream) {
-    if (!Buffer.isBuffer(chunk)) {
-      throw new TypeError('readAll: expected Buffer chunks (stream must be in binary mode)');
-    }
-    chunks.push(chunk);
-  }
-  return Buffer.concat(chunks).toString('utf8');
-}
-
 // endregion | Helpers
diff --git a/packages/agents/src/kb-edit/cli.ts b/packages/agents/src/kb-edit/cli.ts
index 23b3194f..64bc3ec1 100644
--- a/packages/agents/src/kb-edit/cli.ts
+++ b/packages/agents/src/kb-edit/cli.ts
@@ -13,6 +13,8 @@ import { loadAliases } from '@codeassembly/kb/tags';
 
 import type { ResolvedKb } from '../kb-shared/resolve-writable-kb.ts';
 import { resolveWritableKb } from '../kb-shared/resolve-writable-kb.ts';
+import { parseTagList } from '../kb-shared/tag-helpers.ts';
+import { readAll } from '../lib/stream-helpers.ts';
 import { commitSupersede } from './commit-supersede.ts';
 import { loadNote } from './load-note.ts';
 import { append } from './operations/append.ts';
@@ -417,18 +419,6 @@ async function runSupersedeWith(input: {
   return success;
 }
 
-/** Reads a readable stream to completion as a UTF-8 string. */
-async function readAll(stream: Readable): Promise<string> {
-  const chunks: Buffer[] = [];
-  for await (const chunk of stream) {
-    if (!Buffer.isBuffer(chunk)) {
-      throw new TypeError('readAll: expected Buffer chunks (stream must be in binary mode)');
-    }
-    chunks.push(chunk);
-  }
-  return Buffer.concat(chunks).toString('utf8');
-}
-
 /** A captured operation flag: its canonical name plus the value (if any) that followed it. */
 interface SelectedOp {
   name: OperationName;
@@ -563,12 +553,4 @@ function matchOperationFlag(
   return null;
 }
 
-/** Splits a comma-separated tag string into individual tags, dropping empties and trimming whitespace. */
-function parseTagList(value: string): string[] {
-  return value
-    .split(',')
-    .map((tag) => tag.trim())
-    .filter((tag) => tag.length > 0);
-}
-
 // endregion | Helpers
diff --git a/packages/agents/src/kb-shared/__tests__/tag-helpers.test.ts b/packages/agents/src/kb-shared/__tests__/tag-helpers.test.ts
new file mode 100644
index 00000000..53259180
--- /dev/null
+++ b/packages/agents/src/kb-shared/__tests__/tag-helpers.test.ts
@@ -0,0 +1,29 @@
+import { describe, expect, it } from 'vitest';
+
+import { parseTagList } from '../tag-helpers.ts';
+
+describe(parseTagList, () => {
+  it('splits a comma-separated string into individual tags', () => {
+    expect(parseTagList('alpha,beta,gamma')).toEqual(['alpha', 'beta', 'gamma']);
+  });
+
+  it('trims surrounding whitespace from each tag', () => {
+    expect(parseTagList(' alpha , beta ,gamma ')).toEqual(['alpha', 'beta', 'gamma']);
+  });
+
+  it('drops empty segments from leading, trailing, and doubled commas', () => {
+    expect(parseTagList(',alpha,,beta,')).toEqual(['alpha', 'beta']);
+  });
+
+  it('returns a single-element list for a value with no commas', () => {
+    expect(parseTagList('alpha')).toEqual(['alpha']);
+  });
+
+  it('returns an empty list for an empty string', () => {
+    expect(parseTagList('')).toEqual([]);
+  });
+
+  it('returns an empty list for whitespace and commas only', () => {
+    expect(parseTagList(' , , ')).toEqual([]);
+  });
+});
diff --git a/packages/agents/src/kb-shared/tag-helpers.ts b/packages/agents/src/kb-shared/tag-helpers.ts
new file mode 100644
index 00000000..f758f485
--- /dev/null
+++ b/packages/agents/src/kb-shared/tag-helpers.ts
@@ -0,0 +1,10 @@
+/**
+ * Splits a comma-separated tag string into individual tags, dropping empties and trimming whitespace.
+ * @internal
+ */
+export function parseTagList(value: string): string[] {
+  return value
+    .split(',')
+    .map((tag) => tag.trim())
+    .filter((tag) => tag.length > 0);
+}
diff --git a/packages/agents/src/lib/__tests__/stream-helpers.test.ts b/packages/agents/src/lib/__tests__/stream-helpers.test.ts
new file mode 100644
index 00000000..81969c8e
--- /dev/null
+++ b/packages/agents/src/lib/__tests__/stream-helpers.test.ts
@@ -0,0 +1,27 @@
+import { Readable } from 'node:stream';
+
+import { describe, expect, it } from 'vitest';
+
+import { readAll } from '../stream-helpers.ts';
+
+describe(readAll, () => {
+  it('concatenates multiple Buffer chunks into a single UTF-8 string', async () => {
+    const stream = Readable.from([Buffer.from('hello '), Buffer.from('world')]);
+    await expect(readAll(stream)).resolves.toBe('hello world');
+  });
+
+  it('decodes multi-byte UTF-8 sequences split across chunk boundaries', async () => {
+    const encoded = Buffer.from('café', 'utf8');
+    const stream = Readable.from([encoded.subarray(0, 4), encoded.subarray(4)]);
+    await expect(readAll(stream)).resolves.toBe('café');
+  });
+
+  it('returns an empty string for a stream with no chunks', async () => {
+    await expect(readAll(Readable.from([]))).resolves.toBe('');
+  });
+
+  it('throws a TypeError when a chunk is not a Buffer', async () => {
+    const stream = Readable.from(['not-a-buffer'], { objectMode: true });
+    await expect(readAll(stream)).rejects.toThrow(TypeError);
+  });
+});
diff --git a/packages/agents/src/lib/stream-helpers.ts b/packages/agents/src/lib/stream-helpers.ts
new file mode 100644
index 00000000..3c7cd73d
--- /dev/null
+++ b/packages/agents/src/lib/stream-helpers.ts
@@ -0,0 +1,17 @@
+import type { Readable } from 'node:stream';
+
+/**
+ * Reads a readable stream to completion as a UTF-8 string. Callers pass `process.stdin` (binary mode) or a
+ * `Readable.from([Buffer])`, both of which emit `Buffer` chunks.
+ * @internal
+ */
+export async function readAll(stream: Readable): Promise<string> {
+  const chunks: Buffer[] = [];
+  for await (const chunk of stream) {
+    if (!Buffer.isBuffer(chunk)) {
+      throw new TypeError('readAll: expected Buffer chunks (stream must be in binary mode)');
+    }
+    chunks.push(chunk);
+  }
+  return Buffer.concat(chunks).toString('utf8');
+}
diff --git a/packages/agents/src/update-jira-ticket/cli.ts b/packages/agents/src/update-jira-ticket/cli.ts
index e0a26d1b..da8d546d 100644
--- a/packages/agents/src/update-jira-ticket/cli.ts
+++ b/packages/agents/src/update-jira-ticket/cli.ts
@@ -8,23 +8,11 @@
 
 import { realpathSync } from 'node:fs';
 import process from 'node:process';
-import type { Readable } from 'node:stream';
 import { fileURLToPath } from 'node:url';
 
+import { readAll } from '../lib/stream-helpers.ts';
 import { check } from './check.ts';
 
-/** Read every chunk of `stream` and concatenate into a single UTF-8 string. */
-async function readAll(stream: Readable): Promise<string> {
-  const chunks: Buffer[] = [];
-  for await (const chunk of stream) {
-    if (!Buffer.isBuffer(chunk)) {
-      throw new TypeError('readAll: expected Buffer chunks (stream must be in binary mode)');
-    }
-    chunks.push(chunk);
-  }
-  return Buffer.concat(chunks).toString('utf8');
-}
-
 /** Top-level entry: read stdin, run the check, emit JSON. */
 async function main(): Promise<void> {
   try {