fix(ingestion): ingest non-existent absolute-looking strings as text [SDK-234] (gh #3887, follow-up to #3892)

[rshkarin]

Description

Follow-up to #3892 (now merged to dev), closing the remaining half of #3887.

#3892 stops the Windows ValueError crash by guarding the absolute-path branch of save_data_item_to_storage with is_absolute(). This PR fixes the other half of the report: a /-prefixed string that is not an actual file (e.g. a text note like /remember to call Bob about the meeting) should be ingested as text, not turned into a file:// URI pointing at a file that does not exist.

The absolute-path branch converted unconditionally, whereas the relative-path branch right below it already required the file to exist (abs_path.is_file()). I made the two consistent by reusing that same, already-computed abs_path: an absolute-looking string is only turned into a file:// URI when it points at an existing file — otherwise it falls through to text ingestion, on every platform. The ACCEPT_LOCAL_FILE_PATH=false rejection of existing local files is unchanged.

While tracing the callers I found the dry-run estimator (cognee/modules/cognify/estimator.py) deliberately mirrors this routing, and it was raising "file does not exist" for missing absolute paths. Since a real run now treats those as text, I updated _path_candidate to match (missing path → raw text; the gate rejects only existing absolute files) and adjusted its two tests.

Behavior note: because the branch now keys on "existing file" (is_file()), a handful of absolute-looking strings that are not regular files also route to text instead of a file:// URI — an existing directory path, a broken symlink, and pathological paths that error during resolve() (embedded null / over-length). This is intended and safe: none of those are ingestible files, and directories are normally expanded upstream by resolve_data_directories before reaching here. It also repairs a latent downstream break — before this change a /-prefixed note produced a broken file:// URI that get_data_file_path turned into a non-existent path and the loader then failed on.

#3892 has merged to dev; this PR is rebased on top of it and now contains only the follow-up commits.

Acceptance Criteria

• save_data_item_to_storage("/remember to call Bob about the meeting") is ingested as text — no file:// URI, no crash — on Windows, macOS and Linux.
• An existing absolute file path still converts to a file:// URI; with ACCEPT_LOCAL_FILE_PATH=false it still raises IngestionError.
• The dry-run estimate prices a missing absolute path as text instead of erroring out.
• The regression tests run on the regular (Linux) unit-test CI, not only the Windows OS matrix. Verified locally: 38 passed, 1 skipped (the genuine drive-anchored Windows case); ruff format + ruff check clean.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Code refactoring
• Other (please specify):

Pre-submission Checklist

• I have tested my changes thoroughly before submitting this PR (See CONTRIBUTING.md)
• This PR contains minimal changes necessary to address the issue/feature
• My code follows the project's coding standards and style guidelines
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if applicable)
• All new and existing tests pass
• I have searched existing PRs to ensure this change hasn't been submitted already
• I have linked any relevant issues in the description
• My commits have clear and descriptive messages

DCO Affirmation

I affirm that all code in every commit of this pull request conforms to the terms of the Topoteretes Developer Certificate of Origin.

[github-actions]

Hello @rshkarin, thank you for submitting a PR! We will respond as soon as possible.