When injecting system instructions into the chat prompt, include:
1. **Operating system** and **working directory** from the
`workspace_agents` table
2. **Home-level instructions** from `~/.coder/AGENTS.md` (existing
behavior)
3. **Project-level instructions** from `<pwd>/AGENTS.md` (new)
The XML tag is renamed from `<coder-home-instructions>` to
`<system-instructions>` since it now carries more than just the home
instruction file.
### Example output (both files present)
```xml
<system-instructions>
Operating System: linux
Working Directory: /home/coder/coder
Source: /home/coder/.coder/AGENTS.md
... home instructions ...
Source: /home/coder/coder/AGENTS.md
... project instructions ...
</system-instructions>
```
### Example output (no AGENTS.md files)
```xml
<system-instructions>
Operating System: linux
Working Directory: /home/coder/coder
</system-instructions>
```
### Changes
- **`coderd/chatd/instruction.go`**:
- Renamed types: `homeInstructionContext` → `agentContext`, added
`instructionFile` struct
- Extracted `readInstructionFileAtPath` shared helper
- Added `readWorkingDirectoryInstructionFile` to read `<pwd>/AGENTS.md`
- Replaced `formatHomeInstruction` with `formatInstructions` that
renders both files under `<system-instructions>`
- **`coderd/chatd/chatd.go`**:
- Renamed `resolveHomeInstruction` → `resolveInstructions`; now reads
both home and pwd instruction files
- `resolveAgentContext` returns `agentContext` (renamed from
`homeInstructionContext`)
- pwd file read is skipped gracefully if directory is empty or file
doesn't exist
- **`coderd/chatd/instruction_test.go`**:
- Added `TestReadWorkingDirectoryInstructionFile` (success, not-found,
empty-directory)
- Replaced `TestFormatHomeInstruction` with `TestFormatInstructions`
covering all combinations
- Added ordering test (`AgentContextBeforeFiles`) to verify OS/pwd
appear before file sources
Kyle Carberry