VS Code extension 2.1.126: historical sessions not shown in sidebar or /resume (CLI works) — regression

Summary

In the Claude Code VS Code extension v2.1.126, the sidebar "Local" sessions panel and the /resume slash command in chat do not list any historical sessions — they only show currently-active tabs.

The bundled CLI claude --resume (run from a regular terminal) does list all the historical sessions correctly. So the file layer and core listing logic are healthy; the regression is in the extension's UI listing path.

The user reports this view worked correctly ~3 weeks ago (around mid-April 2026).

Environment

• OS: Windows 11 Enterprise 26200
• Extension: anthropic.claude-code 2.1.126-win32-x64
• Workspace path: a:\Source (mapped drive; Resolve-Path returns A:\Source, NTFS is case-insensitive on this dir)
• ~80 historical session JSONL files in ~/.claude/projects/a--Source/, ranging from April to today

Reproduction

1. Open a workspace in VS Code that has many historical sessions in ~/.claude/projects/<encoded-path>/.
2. Open the Claude Code sidebar → "Local" tab → only currently-open tabs are shown, no history.
3. Type /resume inside an open Claude Code chat → no historical sessions appear in the picker.
4. From a regular PowerShell terminal in the same workspace, run claude --resume → all historical sessions are listed correctly.

What was verified directly

1. Files are intact and complete — JSONL files contain valid user/assistant entries (e.g. one file is 2 MB with 75 "type":"user" lines) and end with {"type":"ai-title","aiTitle":"...","sessionId":"..."} lines.
2. Title markers present in all sampled files — aiTitle appears within the first 64 KB of every sampled file (positions 3,882 / 5,541 / 34,287 bytes for three sample files of 894 KB / 298 KB / 1.47 MB), well within the head chunk size F2 = 65536 used by xz4.
3. The filter logic in extension.js should accept these files — at line 161, c5(G,"customTitle")||c5(x,"customTitle")||c5(G,"aiTitle")||c5(x,"aiTitle") finds a title in the head/tail chunks; c5 (defined on line 158) returns the last matching "key":"value" occurrence in a string.
4. The bundled CLI lists everything correctly from the same workspace — same claude.exe that ships in the extension's resources/native-binary/ folder.

Hypothesis

The bug is between the listing function (gz4 → Qz4 → xU → $l) and the webview UI message-passing layer. The listing logic itself works (the CLI proves it), but results don't reach either the sidebar Local panel or the /resume picker. Possibly related to:

• A stale extension-globalState cache that isn't invalidated when the bundled CLI updates the on-disk format
• A change to il(V) (which calls realpath + normalize("NFC")) producing a different path than the writer uses (a:\Source vs realpath result A:\Source — though NTFS is case-insensitive here)
• A new filter/predicate added since the last working version that incorrectly drops files

Workarounds

• Use claude --resume from a regular terminal instead of /resume in chat — this works.
• Downgrade the extension to a version from ~mid-April 2026.