Suggestion: session-pin workspace for stable macOS tool path resolution

[hawkff]

Fixes #11

What

• add per-session workspace pinning for plugin tool-hook path resolution
• persist the first valid non-config workspace path per sessionID and reuse it if later calls lose worktree
• harden config-dir detection by using path.relative(...) ancestry checks instead of string-prefix matching
• avoid resolving relative file/shell tool paths into ~/.config/opencode when context is ambiguous
• bound in-memory session workspace cache growth with a small cap

Why

This attempt to make workspace selection stable for the lifetime of a session, preventing path drift away from the active repo.

Tests

• added regression test:
  • tests/unit/plugin-tools-hook.test.ts
  • verifies workspace is pinned from worktree and reused when later context omits worktree and only provides config-dir directory
• also keeps existing worktree/config-dir resolution coverage

Validation

• bun test tests/unit/plugin-tools-hook.test.ts
• tmp_home=$(mktemp -d) && HOME="$tmp_home" bun run test:ci:unit && rm -rf "$tmp_home"
• bun run test:ci:integration
• bun run build

[remy90]

Frustratingly, even #11 (comment) no longer works. Write access outside of the opencode config directory did work once but it hasn't worked since.
Hopefully I'll get some time at the weekend to investigate this further if it's not fully resolved before then

EDIT:
To clarify the above, I checked out your PR branch, built it and tested a cursor-acp model
in a directory outside of ~/.config/
The same results were seen between main and this branch as far as write access is concerned

[Nomadcxx]

This is waaaay better than my initial fix/patch @hawkff

The problem IMO and we can't be certain unless we add some logging here but..

path.relative() is case-sensitive BUT macOS filesystems aren't. If homedir() returns /Users/Username/.config/opencode and opencode passes /Users/username/.config/opencode (different case), these are the same directory on macOS - but isWithinPath() treats them as different, so the config dir gets accepted as a valid workspace.

The Maybe Fix

Use realpathSync() to normalize paths before comparing:

import { realpathSync } from "fs";

function getOpenCodeConfigPrefix(): string {
  const configHome = process.env.XDG_CONFIG_HOME
    ? resolve(process.env.XDG_CONFIG_HOME)
    : join(homedir(), ".config");
  const configPath = join(configHome, "opencode");
  try {
    return realpathSync(configPath);
  } catch {
    return configPath;
  }
}

function isWithinPath(root: string, candidate: string): boolean {
  try {
    const realRoot = realpathSync(root);
    const realCandidate = realpathSync(candidate);
    const rel = relative(realRoot, realCandidate);
    return rel === "" || (!rel.startsWith("..") && !isAbsolute(rel));
  } catch {
    const rel = relative(root, candidate);
    return rel === "" || (!rel.startsWith("..") && !isAbsolute(rel));
  }
}

realpathSync() resolves symlinks AND normalizes case on macOS, so paths compare correctly.

[hawkff]

What it adds:

• realpath-aware workspace/config path comparison in src/plugin.ts
• macOS-safe handling for case-variant path aliases during config-dir detection
• regression test for symlink-alias config path (tests/unit/plugin-tools-hook.test.ts)

[hawkff]

Hope this helps 🙈