build(deps): pin langchain family to 0.3.x/0.1.x lines to fix broken installs

[wilsonhj]

Why this PR exists

pyproject.toml currently has no upper bound on the langchain family. A fresh pip install connectchain / uv sync today resolves langchain 1.x, which removed langchain.chains, langchain.schema, and langchain.llms — modules this codebase imports throughout. Result: every import of connectchain fails (ModuleNotFoundError) and the test suite is uncollectable on a clean environment.

What it does

Adds upper bounds pinning to the lines the code actually targets — a 4-line diff, nothing else:

langchain>=0.3.26,<0.4.0
langchain-openai>=0.3.24,<0.4.0
langchain-community>=0.3.26,<0.4.0
langchain-mcp-adapters>=0.1.0,<0.2.0

Verification

• uv sync --dev resolves langchain==0.3.30 (0.3.x line) and python -c "import connectchain" succeeds on a clean env.
• Full unit suite: 57 passed / 1 failed — the single failure (test_model_with_unsupported_provider) is pre-existing on main and unrelated to dependency resolution (it asserts an outdated error message; a separate PR addresses it).

Sequencing

This is the first of a small series of focused PRs (dependency pin → sanitizer/orchestrator fixes → model/session/config fixes → MCP fixes → docs). The later PRs each include this pin so they build standalone; those hunks rebase away once this merges.

Co-authored-by: Claude noreply@anthropic.com

[wilsonhj]

Runtime verification — PASS ✅

Verified by runtime observation (dependency resolution + package import), not by test suite. Two fully separate fresh venvs (Python 3.11.14), forced fresh resolves (isolated cache).

With the pin (this branch): resolves langchain 0.3.30 / langchain-core 0.3.86 / langchain-openai 0.3.35 / langchain-mcp-adapters 0.1.14; import connectchain + submodule imports all succeed; uv pip check → "All installed packages are compatible."

Counterfactual (parent commit, unpinned, fresh resolve): resolves langchain 1.3.11 and explodes on the first line of the package:

File ".../connectchain/__init__.py", line 15, in <module>
    from langchain.chains.api.base import APIChain
ModuleNotFoundError: No module named 'langchain.chains'

All three removed module families (langchain.chains, langchain.schema, langchain.llms) are imported across 7 source files and are gone in 1.x.

Worth knowing: the unpinned pip install itself exits 0 — the breakage is import-time only, so a fresh install looks fine until first use (or test collection). That's why this pin matters even though installs "work" today.

[wilsonhj]

Preetam,Excellent. I’m glad to see my PR’s are being merged.I also did testing and analysis of the amex jest-image-snapshot repo. After forking and testing the code, my analysis found a number of bugs. Can you help me escalate these PR’s to package maintainers for review?Secondly, have you reviewed my follow up PR’s in the connect chain repo? Jest-image-snapshot PR’s for review: fix: surface the real error when the diff child process fails by wilsonhj · Pull Request #406 · americanexpress/jest-image-snapshotgithub.com fix: store received image for new snapshots in CI when storeReceivedOnFailure is set by wilsonhj · Pull Request #405 · americanexpress/jest-image-snapshotgithub.comfeat: warn when a 'percent' failureThreshold is set above 1 by wilsonhj · Pull Request #404 · americanexpress/jest-image-snapshotgithub.comConnectChain Fix PR’s: fix: model init, session cache, retry semantics; config accessors raise AttributeError for missing keys by wilsonhj · Pull Request #11 · americanexpress/connectchaingithub.comfix: MCP loader/agent — empty-list semantics, collision warning, kwargs forwarding, concurrent execution by wilsonhj · Pull Request #12 · americanexpress/connectchaingithub.comDocumentation PR:docs: add architecture guide, developer guide, and roadmap by wilsonhj · Pull Request #13 · americanexpress/connectchaingithub.comDo you have any questions?Best,Hiro JamesFounder @ Shiba_Software_Consulting / A.I. SWESent from my iPadOn Jul 16, 2026, at 14:34, Preetam Matta ***@***.***> wrote: Merged #10 into main. —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: ***@***.***>