Lets subagents report context files back to the job board (surfaced from the read tool) so the parent session's next-turn context includes what a background child has been looking at.
Adds the task tool and subagent spawner in harness-tools, and wires spawning/aliasing/reuse and depth limits through harness-app and the job board, so an orchestrator session can launch and track child sessions.
Ports opencode's multi-strategy string-replacer chain (and its test table) into harness-tools::edit, giving the edit tool the same fuzzy-match fallback behavior opencode relies on.
Implements the first five harness-tools: read, write, bash (with timeout/output truncation), glob, and grep, plus shared path-resolution helpers. Wires them into the core tool registry and processor.
Sets up the Cargo workspace (harness-core, harness-tools, harness-providers, harness-mcp, harness-lsp, harness-app, harness-tui) and the ten architecture docs under docs/. harness-core gets its foundational types (session/message/part/model ids), an in-process event bus, a table-driven permission evaluate function, and a SQLite-backed storage actor with schema and roundtrip coverage. Every crate compiles empty and a bin stub prints its version.
darman