fix(skill): skill directory context missing or URL-encoded in system prompt and slash-command paths #33786

Description

Skills with bundled resources (references/, scripts/) fail to resolve file paths in two distinct code paths. The agent cannot locate files relative to the skill's install directory.

#18370 documented the surface symptom ("paths resolved against CWD instead of skill dir") but was closed by #33580, which only fixed one of three occurrences. Two gaps remain:

1. System prompt <available_skills> still URL-encodes <location>

Skill.fmt() in packages/opencode/src/skill/index.ts emits <location>${pathToFileURL(skill.location).href}</location>. This is the same pathToFileURL bug #33580 fixed in the skill tool's base directory output, but this second occurrence in the system prompt was missed. When a skill lives in a git-tagged plugin cache dir (e.g. ...git#v1.3.0), the agent sees ...git%23v1.3.0 in the system prompt and cannot use the path.

2. Skills invoked as slash commands get no directory context at all

When a user types /skill-name, the skill is registered as a command (packages/opencode/src/command/index.ts) whose template is just item.content — the raw SKILL.md body. Unlike the skill tool output, there is no Base directory hint and no <skill_files> list. The agent has no idea where the skill's files are, so relative paths in SKILL.md resolve against CWD. This is the broader issue @zcutlip and @micha149 described in #18370 comments.

Plugins

writing-humanizer@git+https://github.com/shyuan/writing-humanizer.git#v1.3.0 (triggers bug 1); any skill with references/ or scripts/ invoked via /skill-name (triggers bug 2)

OpenCode version

1.17.5

Steps to reproduce

Bug 1: Install a plugin from a git URL with #tag. The <available_skills> block in the system prompt shows <location> with %23 instead of #.

Bug 2: Create a skill with a references/ folder. Invoke it via /skill-name. The agent receives only the SKILL.md text — no base directory, no file list. Ask it to read a reference file; it resolves the path against CWD and fails.

Screenshot and/or share link

Related: #18370 (closed, not fully resolved), #23885 (ACP file:/// prefix), #33580 (fixed the skill tool's base directory but not these two paths)

Operating System

macOS 15.5

Terminal

iTerm2