fix: improve LinkedIn API posting and authenticationv1.2.4

- Add token validation before using cached credentials to prevent stale token issues
- Add proper error handling for image upload initialization with helpful 426 messages
- Skip data URI images instead of attempting to download them
- Update default LinkedIn API version to 202601 (January 2026) - latest active version
- Fix re-authentication flow for expired tokens

Amp-Thread-ID: https://ampcode.com/threads/T-019c6d28-4526-7738-b593-9bd584baa478
Co-authored-by: Amp <amp@ampcode.com>

1 files changed, 94 insertions, 0 deletions

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+# AGENTS.md
+
+## Project Overview
+
+Gos (Go Social Media) is a Go-based command-line tool for scheduling and managing social media posts to Mastodon and LinkedIn. It serves as a replacement for Buffer.com, allowing users to queue and schedule posts from the terminal.
+
+## Project Structure
+
+```
+gos/
+├── cmd/
+│   ├── gos/       # Main gos binary
+│   └── gosc/      # Gos Composer binary (quick post composition)
+├── internal/
+│   ├── colour/    # Terminal color utilities
+│   ├── config/    # Configuration management
+│   ├── entry/     # Post entry handling
+│   ├── oi/        # Output/input utilities
+│   ├── platforms/ # Social media platform implementations
+│   │   ├── linkedin/
+│   │   ├── mastodon/
+│   │   ├── noop/
+│   │   └── platform.go
+│   ├── prompt/    # User prompts
+│   ├── queue/     # Message queue management
+│   ├── schedule/  # Posting schedule logic
+│   ├── summary/   # Gemini gemtext summary generation
+│   ├── table/     # Table output formatting
+│   ├── tags/      # Share tag parsing
+│   ├── timestamp/ # Timestamp utilities
+│   ├── main.go
+│   ├── run.go
+│   └── version.go
+├── docs/          # Documentation and images
+├── examples/      # Example files
+└── gosdir/        # Example gos directory structure
+```
+
+## Build System
+
+This project uses [Mage](https://magefile.org/) for build automation.
+
+### Commands
+
+| Command | Description |
+|---------|-------------|
+| `mage` or `mage build` | Build `gos` and `gosc` binaries |
+| `mage install` | Build and install binaries to `~/go/bin` |
+| `mage clean` | Remove built binaries |
+| `mage test` | Run all tests |
+| `mage fuzz` | Run fuzz tests (10s) |
+| `mage lint` | Run golangci-lint |
+| `mage vet` | Run `go vet` |
+| `mage dev` | Run tests, vet, lint, then build with race detector |
+| `mage devInstall` | Install `gopls` and `golangci-lint` |
+
+### Before Committing
+
+Run `mage dev` to ensure tests pass, vet and lint checks succeed, and the build completes with race detection.
+
+## Testing
+
+- Tests use the standard Go testing framework
+- Test files follow the `*_test.go` naming convention
+- Run tests: `mage test` or `go test -v ./...`
+- Run fuzz tests: `mage fuzz` or `go test ./internal/entry/ -fuzz=FuzzExtractURLs -fuzztime=10s`
+
+## Code Conventions
+
+- **Go version**: 1.23+
+- **Module path**: `codeberg.org/snonux/gos`
+- **Package layout**: Internal packages under `internal/`, commands under `cmd/`
+- **Error handling**: Standard Go error handling patterns
+- **Dependencies**: Minimal external dependencies (fatih/color, golang.org/x packages)
+
+### Go Coding Practices
+
+Follow the practices defined in `/home/paul/git/conf/snippets/go/go-projects/go-projects.md`:
+
+## Linting
+
+Uses `golangci-lint`. Install with:
+```bash
+go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+```
+
+Or run `mage devInstall`.
+
+## Key Dependencies
+
+- `github.com/fatih/color` - Terminal colors
+- `golang.org/x/oauth2` - OAuth2 for LinkedIn
+- `golang.org/x/net` - HTML parsing for LinkedIn previews
+- `github.com/magefile/mage` - Build automation