Changes for 0.7.0

[Idleness76]

Description

This PR prepares the 0.7.0 release of Weavegraph. The branch comprises several large commits of targeted revision work, documentation improvements, breaking API removals, and a license change from MIT to Apache-2.0. The release includes over 6K lines of net code reduction through module-wide refactoring, dead code removal, documentation condensing, and control flow simplification across the entire codebase, while maintaining backward compatibility where possible and clearly documenting breaking changes.

Type of Change

• Breaking change (removes several public APIs and changes migration SQL checksums)
• Refactoring (no functional changes across most modules)
• Documentation update (migration guide, release notes, code comments)
• Test improvements (two batches of test revisions)
• License change (MIT → Apache-2.0)

Changes Made

License & Legal

• Migrated from MIT to Apache-2.0 license across all source files
• Updated LICENSE, CHANGELOG, CONTRIBUTING, and SECURITY documentation

Core API Changes & Breaking Items

• LLMStreamingEvent: Removed LLMStreamingEvent::new(...) constructor; use LLMStreamingEvent::builder(chunk) or factory methods (chunk_event, final_event, error_event)
• NodeContext: Removed emit_node() method; use emit(scope, message) instead
• Error types: Removed PersistenceError::MissingField and SQLiteCheckpointerError; use CheckpointerError directly
• Private modules: checkpointer_postgres_helpers and checkpointer_sqlite_helpers are now private implementation details
• Unused public APIs trimmed: IdError, ParsedId, IdGenerator::{generate_uuid, generate_random_id, parse_id, current_counter, reset_counter}, id_utils, JsonValueExt::deep_clone, merge_inspector, message_id_helpers, type_guards
• Breaking (Migration SQL Checksums): Migration SQL files were rederived with equivalent schemas but changed file contents. Existing databases will produce a hard sqlx checksum error on next connect() call — no schema changes, only checksum record correction required. See v0.7.0 migration guide.

Public API Improvements

• LLMStreamingEventBuilder — fluent builder for constructing LLM streaming events with optional session_id, node_id, stream_id, is_final, scope, metadata, timestamp fields
• conditional_edges() now returns &[ConditionalEdge] instead of &Vec<ConditionalEdge> (transparently coercible; explicit &Vec<_> annotations should be updated)
• WeaveError now derives Default
• MetricsObserver simplification — now uses default no-op RuntimeObserver::on_invocation_start implementation

Code Quality & Maintenance

• Heavy revision pass across all modules: src/app.rs, src/channels/, src/control.rs, src/event_bus/, src/graphs/, src/llm/, src/message.rs, src/node.rs, src/reducers/, src/runtimes/, src/schedulers/, src/state.rs, src/telemetry/, src/types.rs, src/utils/
  • Documentation condensed and clarified
  • Dead code and unreachable branches removed
  • Control flow simplified for readability
  • Private helpers renamed for clarity
  • All formatting and lint issues resolved
• Test revisions (2 batches): Improved test structure, assertions, and maintenance
• Minor cosmetic cleanups: EventBus::with_sink, Channel::set_version, VersionedStateBuilder
• Fixed misapplied attributes: Removed #[must_use] from mutating VersionedState::{add_message, add_extra} methods
• Rustdoc fixes: Resolved nightly doc build warnings (e.g., IdGenerator doctest reserved keyword issue)
• Likely more things that I'm forgetting...

Documentation

• Updated docs/MIGRATION.md with comprehensive v0.7.0 migration guide for SQL checksum mismatch
• Updated docs/ARCHITECTURE.md and other architecture docs for clarity
• Improved examples and documentation in examples/README.md
• Prepared CHANGELOG.md with complete 0.7.0 release notes

Testing

• Existing tests pass (cargo test)
• Clippy lints resolved (cargo clippy)
• Code formatted (cargo fmt)
• No new warnings on nightly (cargo +nightly doc)
• All test revisions completed and passing

Checklist

• My code follows the project's code style (cargo fmt)
• I have run clippy and addressed warnings (cargo clippy)
• I have updated documentation (migration guide, release notes, architecture)
• All existing tests pass locally
• I have updated CHANGELOG.md with 0.7.0 release notes
• Breaking changes are clearly documented in CHANGELOG and migration guide
• License headers updated to Apache-2.0

Breaking Changes

This is a breaking release — 0.7.0. Migration is straightforward for most users:

1. API Removals: Update imports and usages:

   • LLMStreamingEvent::new(...) → LLMStreamingEvent::builder(chunk).build()
   • NodeContext::emit_node(...) → NodeContext::emit(scope, message)
   • Remove usage of deleted types/functions listed above

2. Migration SQL Checksum (All Persistence Users):

   • SQLite: Affected by default
   • PostgreSQL: Affected if postgres-migrations feature enabled
   • Symptom: Hard sqlx checksum validation error on next app startup
   • Fix: Follow exact SQL and step-by-step Docker upgrade instructions
   • Important: No data loss — only checksum record correction needed

See CHANGELOG.md [0.7.0] section and docs/MIGRATION.md for complete details.

Additional Notes

• Net code reduction: ~6.2K lines (removal of unused public APIs, dead code, documentation condensing)
• 118 files modified across 15 commits
• All changes are backward compatible except where explicitly marked as breaking
• This release maintains the project's stability while significantly improving code maintainability