feat(redirect-links): stage util to append ?u= on openhm.xyz URLs (#1164)

[oxoxDev]

Summary

Stage a rust util that appends ?u=<user_id> to every openhm.xyz/<id> URL in a string. Util-only — no call sites yet; the wire-up belongs in a follow-up once openhm.xyz URL emission lands client-side (today the repo only emits internal openhuman://link/<id>).

Problem

Per #1164, every public openhm.xyz/<id> short URL surfaced to the user must carry ?u=<user_id> so the redirect service can attribute clicks and resolve user-scoped state. Today grep -rn "openhm.xyz" src/ returns no hits — the public form is produced backend-side. This PR puts the rewrite logic in place so wiring it from a future caller is one line.

Solution

• append_user_id_to_public_links(text, Option<user_id>) -> String in src/openhuman/redirect_links/ops.rs — regex-based, idempotent, URL-encodes user_id, preserves existing query strings, anchored on https?:// so lookalike domains (evil-openhm.xyz, openhm.xyz.evil.com) do not match.
• rewrite_outbound_for_user(config, text, Option<user_id>) — convenience wrapper running the existing rewrite_outbound then injecting ?u=.
• Re-exported from redirect_links::mod.
• 10 inline #[cfg(test)] cases cover bare URL, existing query, idempotent, None user, no-URL, multi-URL, special-char encoding, lookalike rejection, surrounding text/punctuation, and the wrapper roundtrip.

Submission Checklist

• Tests added — 10 inline cases in ops.rs
• cargo check, cargo fmt --check, cargo clippy clean for redirect_links
• cargo test --lib redirect_links green (27 pass)
• Diff coverage ≥ 80%
• [N/A: util-only PR — no call sites today] — no behavior change for existing callers
• [N/A: rust-core only, no frontend touch] — no pnpm gates apply

Impact

Zero runtime impact today (no caller). Stages the substitution layer so a future backend or follow-up PR can wrap outbound text in one call.

Related

Closes #1164. Wire-up deferred to follow-up — confirm with @senamakel whether ?u= injection should land render-time (here) or resolve-time (server-side at openhm.xyz).

Summary by CodeRabbit

• New Features
  • Automatically appends a URL-encoded user identifier to public openhm.xyz links where applicable, preserving surrounding punctuation, handling fragments and existing query parameters, and leaving links unchanged when no identifier is provided or already present.
• Tests
  • Expanded tests covering expansion and outbound rewriting, encoding, multiple matches, idempotency, query/fragment edge cases, lookalike avoidance, and punctuation preservation.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 4eba300a-c2af-4231-8ac5-cf25b8235e76

📥 Commits

Reviewing files that changed from the base of the PR and between 83e46cd and 6e7d5e6.

📒 Files selected for processing (1)

• src/openhuman/redirect_links/ops.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• src/openhuman/redirect_links/ops.rs

---

📝 Walkthrough

Walkthrough

Adds two exported functions that expand internal link placeholders then append a URL-encoded ?u=<user_id> (or &u=) to domain-anchored https://openhm.xyz/... public links. Handles None user IDs, preserves trailing punctuation and fragments, avoids lookalike domains, is idempotent, and includes unit tests.

Changes

User ID Tagging for Public Links

Layer / File(s)	Summary
Data / Pattern src/openhuman/redirect_links/ops.rs	Introduces public_url_regex() that matches only https://openhm.xyz/... (optional query and fragment) to avoid lookalikes and mid-token matches.
Core Implementation src/openhuman/redirect_links/ops.rs	Adds append_user_id_to_public_links(text, user_id) which URL-encodes user_id, preserves trailing sentence punctuation, splits #fragment to insert ?u=/&u= into the query, is idempotent (skips when ?u=/&u= present), no-ops when user_id is None, and supports multiple replacements.
Integration / Flow src/openhuman/redirect_links/ops.rs	Adds rewrite_outbound_for_user(config, text, user_id) that first runs existing rewrite_outbound() to expand openhuman://link/<id> placeholders, then calls append_user_id_to_public_links() on the expanded text.
Public API src/openhuman/redirect_links/mod.rs	Re-exports append_user_id_to_public_links and rewrite_outbound_for_user alongside existing ops, expanding the module's public API surface.
Tests src/openhuman/redirect_links/ops.rs (tests)	Adds unit tests covering bare vs query URLs, idempotency, None user_id, non-matching domains, multiple matches, URL-encoding, lookalike avoidance, punctuation preservation, fragment handling, and an integration-style roundtrip for rewrite_outbound_for_user.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• feat(redirect_links): SQLite-backed URL shortener for token-heavy links #870 — Prior changes to the same redirect_links ops module and export surface that this PR builds upon.

Poem

🐰 I hop through text where short links hide,
I tuck a tiny "u=" at the public side.
I mind the commas, dots, and crafty fakes,
I URL-encode each hop the rabbit makes.
Clicks now carry who came by — a happy little stride.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding a utility function to append user ID query parameters to openhm.xyz URLs.
Linked Issues check	✅ Passed	The PR implements the core utility functions required by #1164, but defers integration with actual call sites to follow-up work.
Out of Scope Changes check	✅ Passed	All changes are scoped to implementing the utility functions and re-exports specified in the linked issue; no unrelated modifications detected.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

---

_{Review rate limit: 3/5 reviews remaining, refill in 14 minutes and 1 second.}

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/openhuman/redirect_links/ops.rs`:
- Around line 34-35: The regex used to match URLs (Regex::new(...) in ops.rs)
currently includes '#' in the query character class, causing appended "u=" to
become part of the fragment for URLs like https://openhm.xyz/abc?foo=bar#frag;
update the regex to exclude '#' from the query charclass (remove '#' from the
class string) and change the tail-appending logic (the code that concatenates
the new param in the block around lines 165–170) to split the matched tail on
'#' into query and fragment parts, insert the "u=..." into the query portion
(adding '?' or '&' as appropriate) and then rejoin with the fragment prefixed by
'#' so the u param is always a query parameter, not part of the fragment.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 394c4d2b-b469-4d8a-8a09-3d1e5de50156

📥 Commits

Reviewing files that changed from the base of the PR and between 995e5cc and 2196f97.

📒 Files selected for processing (2)

• src/openhuman/redirect_links/mod.rs
• src/openhuman/redirect_links/ops.rs