fix: propagate version to components in FileSystemProvider

[martimfasantos]

Summary

FileSystemProvider.extract_components() in filesystem_discovery.py does not pass version=meta.version when constructing Tool, Resource, ResourceTemplate, or Prompt objects from decorated functions. This causes all components discovered through FileSystemProvider to have version=None, breaking version-based deduplication (_dedupe_with_versions) and the meta.fastmcp.version/meta.fastmcp.versions metadata in the MCP wire output.

Problem

When tools are registered using the @tool decorator with a version parameter and discovered via FileSystemProvider, the version information is silently discarded.

Root Cause

In fastmcp/server/providers/filesystem_discovery.py, the extract_components() function reads ToolMeta, ResourceMeta, and PromptMeta from decorated functions but omits the version field when calling *.from_function():

# Current code (lines ~224-238) — version is missing for ALL component types
if isinstance(meta, ToolMeta):
    tool = Tool.from_function(
        obj,
        name=meta.name,
        title=meta.title,
        description=meta.description,
        icons=meta.icons,
        tags=meta.tags,
        output_schema=meta.output_schema,
        annotations=meta.annotations,
        meta=meta.meta,
        task=resolved_task,
        exclude_args=meta.exclude_args,
        serializer=meta.serializer,
        auth=meta.auth,
        # ❌ version=meta.version is MISSING
    )

The same omission applies to the ResourceMeta → Resource/ResourceTemplate and PromptMeta → Prompt branches.

Comparison with LocalProvider

The LocalProvider decorators correctly pass version:

# local_provider/decorators/tools.py — correct
tool = Tool.from_function(
    tool,
    ...,
    version=fmeta.version,  # ✅ version is passed
    ...
)

Impact

1. _meta.fastmcp.version is always missing — Clients relying on tool.meta["fastmcp"]["version"] get None
2. _meta.fastmcp.versions is never populated — The _dedupe_with_versions() function in mcp_operations.py checks c.version is not None to decide whether to inject the versions list. Since all components have version=None, the list is never built.
3. Multi-version tools collapse silently — Two versions of the same tool (e.g., hello_world v1.0 and v2.0 with different Python function names) are treated as unversioned duplicates, and the deduplication picks one arbitrarily instead of by version ordering.
4. Version-targeted call_tool fails — Clients sending _meta.fastmcp.version in call_tool requests won't match specific versions since the server doesn't know tools have versions.

Reproduction

# tools/hello_world.py
from fastmcp.tools import tool

@tool(name="hello_world", version="1.0", description="v1")
def hello_world_v1(name: str) -> str:
    return f"Hello {name}"

@tool(name="hello_world", version="2.0", description="v2")
def hello_world_v2(name: str, age: int) -> str:
    return f"Hello {name}, age {age}"

# client.py
from fastmcp import Client
import asyncio

async def main():
    async with Client("http://localhost:3000/mcp") as client:
        tools = await client.list_tools()
        for t in tools:
            meta = t.meta or {}
            fastmcp = meta.get("fastmcp", {})
            print(f"{t.name}: version={fastmcp.get('version')}, versions={fastmcp.get('versions')}")
            # Expected: hello_world: version=2.0, versions=['2.0', '1.0']
            # Actual:   hello_world: version=None, versions=None

asyncio.run(main())

Fix

Add version=meta.version to all three *.from_function() calls in extract_components():

 if isinstance(meta, ToolMeta):
     tool = Tool.from_function(
         obj,
         name=meta.name,
+        version=meta.version,
         title=meta.title,
         ...
     )
 elif isinstance(meta, ResourceMeta):
     ...
     resource = ResourceTemplate.from_function(
         fn=obj,
+        version=meta.version,
         ...
     )
     ...
     resource = Resource.from_function(
         fn=obj,
+        version=meta.version,
         ...
     )
 elif isinstance(meta, PromptMeta):
     prompt = Prompt.from_function(
         obj,
+        version=meta.version,
         ...
     )

• My change closes #(issue number)
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