Doc mode fix

[MathisWellmann]

• return an Error when opt_crate_name is not set but DocMode uses tools.

[github-actions]

Summary

The PR adds an InvalidDocMode error that agent_builder now returns when a tool-using DocMode is paired with None crate name (previously a silent fall-through that registered no doc tools), and switches the fractal-studio example from false to ThinkingLevel::Medium. The new match arm is correct and ordered after the Some arm; the example call compiles against the impl Into<ThinkingLevel> signature and matches the documented From<bool> semantics.

Issues

None

[github-actions]

Summary

The PR threads ThinkingLevel through the fractal-studio example, adds Error::InvalidDocMode for tool-based DocModes without a host crate, and adjusts one test. The new error arm breaks the documented None behavior and existing call sites, including the example the diff itself touches.

Issues

• examples/fractal-studio/src/main.rs:771, blocker: the call still passes None with DocMode::default() (IndexAndTools, where uses_tools() is true), which now hits the new (None, true) arm in agent_builder and makes the app panic at startup via .expect(...). Fix: pass DocMode::Inline when no host crate is provided.
• symbiont/src/inference/agent_builder.rs:175, major: the same arm breaks every existing None, DocMode::default() call site — examples/quantize/src/main.rs:396, rastrigin:165, fizzbuzz:104, counter:42, sort:248, tictactoe:347, tool-calling:173, batched-evolution:306, symbiont/benches/batch_throughput.rs:616 — and contradicts the doc comments at lines 124 and 211, which say doc_mode "has no effect" when opt_crate_name is None. Either fall through to no-tools for None or update all those call sites and the docs; also no test covers the new Err(InvalidDocMode) path.

[github-actions]

Summary

The PR makes Inline the default DocMode, adds an InvalidDocMode error for opt_crate_name == None with a tools mode, and switches fractal-studio to ThinkingLevel::Medium. It changes documented behavior and defaults without updating the in-file docs.

Issues

• symbiont/src/inference/agent_builder.rs:175 (major): The new (None, true) => Err(InvalidDocMode) arm turns agent_builder(None, IndexAndTools|Tools, ...) from a working no-op into a hard error, but the doc comment in the same file (line 113) still states "With None … doc_mode has no effect." Previously valid calls now break; align the error with the documented contract or fix the doc.
• symbiont/src/system_prompt.rs:185 (major): #[default] moved from IndexAndTools to Inline, so every DocMode::default() host now embeds the full API synopsis in the preamble on every inference request instead of the compact on-demand index — a silent latency/token regression the doc itself warns grows with API size.

[github-actions]

Summary

The PR makes tool-based DocModes a hard error without a host crate name (Error::InvalidDocMode), flips the DocMode default to Inline, and passes ThinkingLevel explicitly in the fractal-studio example. The direction is sound, but it leaves the old "doc_mode has no effect" contract in system_prompt and init_agent docs/tests and adds no test for the new error.

Issues

• Major — symbiont/src/system_prompt.rs (system_prompt doc and test system_prompt_without_crate_ignores_doc_mode): the doc still claims doc_mode "has no effect" with None and the test still asserts success for IndexAndTools/Tools with None, but the new agent_builder arm (agent_builder.rs:175) returns Error::InvalidDocMode for exactly those combinations, so system_prompt can no longer reproduce any agent's preamble for those inputs. Update the doc/test (or reject there too) to match the new contract.
• Major — symbiont/src/inference/agent_builder.rs (init_agent doc, ~line 209): still says "With None, no host API is documented and doc_mode has no effect", yet init_agent(None, DocMode::IndexAndTools, …) now returns Err(InvalidDocMode), and no # Errors section mentions the new variant. Update the docs.
• Major — Missing test for the new behavior: the diff edits the tests module only to fix the existing call's arguments; add an assertion that agent_builder(None, DocMode::Tools, …) fails with Error::InvalidDocMode (the sibling test shows the client builds offline, so no network is needed).

[github-actions]

Summary

The PR makes tool-based DocMode variants require a crate name (new Error::InvalidDocMode, raised in system_prompt and agent_builder) and moves #[default] from IndexAndTools to Inline. The error path is correct and tested, but the default flip silently reconfigures in-repo callers.

Issues

• symbiont/src/system_prompt.rs:186 (major): Moving #[default] to Inline silently changes behavior for examples/evolving-trader/src/main.rs:696 and examples/struct-support/src/main.rs:39, which pass Some(crate) with DocMode::default(). They now get the full API synopsis inlined in every prompt instead of the compact index, lose the api_index/api_doc tools, and lose the DOC_TOOLS_MAX_TURNS budget that agent_builder only sets in its (Some, true) arm (rig's default of 0 turns remains for any own tools). Set DocMode::IndexAndTools explicitly in those examples if the tool mode is intended, and add a test pinning DocMode::default() == Inline so the next default flip cannot silently reconfigure callers again.

[github-actions]

Summary

The PR flips DocMode::default() from IndexAndTools to Inline and makes system_prompt/agent_builder return a new Error::InvalidDocMode when a tools-based mode is combined with None crate; examples and benches are consistent with the new contract. No blocker or major issue found: all DocMode::default() call sites verified via grep use None (behavior unchanged), the two Some(crate) sites were updated to IndexAndTools, From<bool> for ThinkingLevel still exists for the unmodified examples, and the new error path is covered by tests in both system_prompt and agent_builder.

Issues

None

[github-actions]

Summary

The PR flips DocMode's default to Inline and makes tool-based doc modes require a host crate: system_prompt and agent_builder now return a new Error::InvalidDocMode for None + IndexAndTools/Tools, with docs and examples updated to match. I verified all in-repo callers of agent_builder/agent_from_env/system_prompt (examples, benches), the impl Into<ThinkingLevel> signature that keeps false call sites compiling, and the new error tests; the change is internally consistent.

Issues

None