fix(agent): harden harness profile registration and clarify subagent VFS tooling

[barredterra]

Summary

• Guard the Deep Agents harness profile registration with a threading.Lock so concurrent agent runner constructions in one process cannot both register, eliminating a redundant duplicate-register merge and its warning log.
• Document why the source-code-analyzer subagent is declared with tools: []: Deep Agents injects FilesystemMiddleware (and the read-only VFS tools ls, read_file, glob, grep) into every subagent stack regardless of the tools field; the empty list only prevents inheriting the parent's mutation tools.
• Declare langchain, langchain-core, and langgraph as direct, range-pinned dependencies (previously only transitive via deepagents/langchain-openai) so an incompatible resolver resolution surfaces at install time instead of breaking imports.

Test plan

• Edited files parse; no linter errors.
• Module imports and double-registration of the harness profile is a no-op.
• Verify the agent still boots and the source-code-analyzer subagent can read files from /source/ on a dev site.

[greptile-apps]

Confidence Score: 5/5

Both changes are safe to merge: the lock-based registration is correct and the new dependency bounds match what was already being pulled transitively.

The threading change is a well-scoped, low-risk fix to a real but harmless race (previously the duplicate register only caused a warning log). The dependency additions are purely declarative and don't change any runtime behaviour — they only surface resolver conflicts earlier. No functional logic is altered, and the VFS tool injection comment accurately reflects the Deep Agents library's documented behaviour.

No files require special attention; the only open item is the manual test from the PR checklist (verifying the source-code-analyzer subagent can read /source/ on a dev site), which is a runtime integration concern outside the diff.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant T1 as Thread 1 (gunicorn/RQ)
    participant T2 as Thread 2 (gunicorn/RQ)
    participant Lock as _ASK_ALYF_PROFILE_LOCK
    participant Flag as _ASK_ALYF_PROFILE_REGISTERED
    participant DA as register_harness_profile()

    T1->>Lock: acquire
    T2->>Lock: acquire (blocks)
    Lock-->>T1: acquired
    T1->>Flag: check (False)
    T1->>DA: register_harness_profile("openai", profile)
    DA-->>T1: ok
    T1->>Flag: set True
    T1->>Lock: release
    Lock-->>T2: acquired
    T2->>Flag: check (True)
    T2->>Lock: release (return early - no double-register)

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sequenceDiagram
    participant T1 as Thread 1 (gunicorn/RQ)
    participant T2 as Thread 2 (gunicorn/RQ)
    participant Lock as _ASK_ALYF_PROFILE_LOCK
    participant Flag as _ASK_ALYF_PROFILE_REGISTERED
    participant DA as register_harness_profile()

    T1->>Lock: acquire
    T2->>Lock: acquire (blocks)
    Lock-->>T1: acquired
    T1->>Flag: check (False)
    T1->>DA: register_harness_profile("openai", profile)
    DA-->>T1: ok
    T1->>Flag: set True
    T1->>Lock: release
    Lock-->>T2: acquired
    T2->>Flag: check (True)
    T2->>Lock: release (return early - no double-register)

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_{Reviews (1): Last reviewed commit: "chore(deps): declare langchain, langchai..." | Re-trigger Greptile}

[barredterra]

Added a follow-up cleanup commit: removed the five orphaned code-search toolset wrapper methods (search_code, read_code_file, ls, find, grep) that were no longer registered as agent tools after the move to the source-code-analyzer subagent. The underlying tools.* functions remain. All 34 code-tool tests pass.