v0.17.0 — quiet by default + tighter routing instructions

Two-part SessionStart context-cost reduction + targeted tool-description tightening, validated by routing_bench.

Highlights

• SessionStart project_map injection: OFF by default (was tied to adopted state). The decision table + on-demand project_map MCP tool + per-tool descriptions cover every workflow the dump used to support; paying ~2.3 KB/session is wasteful even pre-adopt.
  • Opt in with CODE_GRAPH_VERBOSE_HOOKS=1.
  • Legacy CODE_GRAPH_QUIET_HOOKS=0/1 still wins for backward compat.
• MCP instructions field trimmed 1418 → ~700 B by dropping the 10 per-tool decision rows that already live in tool descriptions and in MEMORY.md → plugin_code_graph_mcp.md. What remains: the boundary signal (which 5 advanced tools are CLI-only, what Grep/Read still cover) and the pointer to the adopted decision table.
• Tool description tightening (LLM-visible):
  • semantic_code_search: now adds "If module path is known, prefer module_overview" — closes the path+concept routing ambiguity.
  • find_references: now adds "For plain literals (string/regex), prefer Grep" — find_references only tracks defined-symbol usage.

Verification

cargo test --release --test routing_bench -- --ignored against anthropic/claude-sonnet-4.5 via OpenRouter:

P@1 = 21/22 = 95.5% (baseline v0.16.7 = 19/20 = 95.0%)

Both new v0.17.0 regression guards passed. Single miss is a pre-existing oracle item (EmbeddingModel struct definition → ast_search vs get_ast_node; semantically defensible — ast_search returns nodes by name+kind), not introduced by this release.

Compat

• v0.9.0 escape hatches preserved via CODE_GRAPH_QUIET_HOOKS.
• computeQuietHooks({ adopted, env }) still accepts adopted (now ignored) — no call-site breakage.
• Auto-update: existing installs will pick this up via the next SessionStart auto-update cycle.

Full prose changelog: CHANGELOG.md.

Full Changelog: v0.16.9...v0.17.0