Add OpenSpec change for operation logging

openspec/changes/add-operation-logging/.openspec.yaml

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+schema: spec-driven
+created: 2026-04-15

openspec/changes/add-operation-logging/design.md

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+## Implementation
+
+### Log File Location
+- Path: `/var/log/declpac.log`
+- Single merged log file (stdout + stderr intermingled in order of arrival)
+
+### State-Modifying Functions (need logging)
+1. `SyncPackages()` - `pacman -S --needed <packages>`
+2. `InstallAUR()` - `git clone` + `makepkg -si --noconfirm`
+3. `MarkAllAsDeps()` - `pacman -D --asdeps`
+4. `MarkAsExplicit()` - `pacman -D --asexplicit <packages>`
+5. `CleanupOrphans()` - `pacman -Rns`
+
+### Functions to Skip (read-only)
+- `DryRun()` - queries only
+- `getInstalledCount()` - pacman -Qq
+
+### Execution Patterns
+
+| Pattern | Functions | How |
+|---------|------------|-----|
+| Streaming | MarkAllAsDeps, MarkAsExplicit, InstallAUR | `io.MultiWriter` to tee to both terminal and log |
+| Captured | SyncPackages, CleanupOrphans | capture with `CombinedOutput()`, write to log, write to terminal |
+
+### Error Handling
+- Write error to log BEFORE returning from function
+- Print error to stderr so user sees it
+
+### Dependencies
+- Add to imports: `io`, `os`, `path/filepath`
+
+### Structure
+
+```go
+// pkg/state/state.go
+var logFile *os.File
+
+func OpenLog() error {
+    logPath := filepath.Join("/var/log", "declpac.log")
+    f, err := os.OpenFile(logPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+    if err != nil {
+        return err
+    }
+    logFile = f
+    return nil
+}
+
+func GetLogWriter() io.Writer {
+    return logFile
+}
+
+func Close() error {
+    if logFile == nil {
+        return nil
+    }
+    return logFile.Close()
+}
+```
+
+### Flow in Sync() or main entrypoint
+1. Call `OpenLog()` at program start, defer close
+2. Each state-modifying function uses `state.GetLogWriter()` via MultiWriter
+
+### Wire into main.go
+- Open log at start of `run()`
+- Pass log writer to pacman package (via exported function or global)

openspec/changes/add-operation-logging/proposal.md

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+## Why
+
+The tool exits without saving the full pacman output, making debugging difficult
+when operations fail. Users need a persistent log of all pacman operations for
+debugging and audit.
+
+## What Changes
+
+- Add state directory initialization creating `~/.local/state/declpac` if not exists
+- Open/manage a single log file at `$XDG_STATE_HOME/declpac` (e.g., `~/.local/state/declpac/declpac`)
+- Instrument all state-modifying exec calls in `pkg/pacman/pacman.go` to tee or append output to this file
+- Skip debug messages (internal timing logs)
+- Capture and write errors before returning
+
+## Capabilities
+
+### New Capabilities
+- Operation logging: Persist stdout/stderr from all pacman operations
+
+### Modified Capabilities
+- None
+
+## Impact
+
+- `pkg/pacman/pacman.go`: Instrument all state-modifying functions to write to log file
+- New module: May create `pkg/state/state.go` or similar for log file management

openspec/changes/add-operation-logging/tasks.md

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+## Tasks
+
+- [x] 1. Create state module
+
+Create `pkg/state/state.go`:
+- `OpenLog()` - opens `/var/log/declpac.log` in append mode
+- `GetLogWriter()` - returns the raw log file writer (for MultiWriter)
+- `Write(msg []byte)` - writes message with timestamp + dashes separator
+- `Close()` - closes the file
+
+- [x] 2. Wire into main.go
+
+In `cmd/declpac/main.go` `run()`:
+- Call `OpenLog()` at start
+- `defer Close()` log
+
+- [x] 3. Instrument pkg/pacman
+
+Modify `pkg/pacman/pacman.go`:
+
+All state-modifying functions use `state.Write()` instead of `state.GetLogWriter().Write()`:
+
+```
+// OLD
+state.GetLogWriter().Write(output)
+
+// NEW
+state.Write(output)  // auto-prepends timestamp
+```
+
+**Functions updated:**
+- `SyncPackages()` - write output with timestamp
+- `CleanupOrphans()` - write output with timestamp
+- `MarkAllAsDeps()` - write operation name with timestamp before running
+- `MarkAsExplicit()` - write operation name with timestamp before running
+- `InstallAUR()` - write "Cloning ..." and "Building package..." with timestamps
+- Error handling - `state.Write([]byte("error: ..."))` for all error paths
+
+- [x] 4. Add io import
+
+Add `io` to imports in pacman.go
+
+- [x] 5. Test
+
+Run a sync operation and verify log file created at `/var/log/declpac.log`