Add NIP-50 search filter support

[wksantiago]

Adds search field to filters for relay full-text search capability.

Summary by CodeRabbit

• New Features

  • Added NIP-50 search support for filters: optional query-based matching with accessors and new match APIs that invoke search callbacks when present.

• Tests

  • Added a comprehensive NIP-50 test suite and test executable covering parsing, cloning, search matching, client message handling, and memory/safety scenarios.

• Documentation

  • Updated README to list NIP-50 as an optional feature.

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[coderabbitai]

Caution

Review failed

The pull request is closed.

Walkthrough

Adds NIP‑50 "search" support: a search field on nostr_filter_t, a search callback type, search-aware matching APIs and accessors, JSON parsing/clone/free updates, a new NIP‑50 test suite, CMake test target, and README feature flag update.

Changes

Cohort / File(s)	Summary
Relay Protocol Header include/nostr_relay_protocol.h	Adds char *search to nostr_filter_t, defines nostr_search_callback_t, and declares nostr_filter_matches_with_search, nostr_filters_match_with_search, nostr_filter_get_search, and nostr_filter_has_search.
Filter Implementation src/relay_filter.c	Parses/validates search from JSON, allocates/frees/clones filter->search, adds nostr_filter_matches_with_search and batch variant, and implements accessors and search-aware matching integration.
Tests & Build tests/CMakeLists.txt, tests/test_nip50.c	Adds test_nip50 target and an extensive NIP‑50 test suite (parsing, cloning, matching, REQ parsing) with Unity and standalone runner support.
Docs / Flags README.md	Adds NIP‑50 to the optional NIPs list exposed via feature flags.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related issues

• NIP-50: Search Capability (Relay) #40: Adds the same search field and search-aware matching APIs; likely the same objective and can be linked.

Possibly related PRs

• Add NIP-50 search filter support #56: Adds NIP‑50 search field, callback type, matching APIs, accessors, parsing/clone/free logic and tests — strongly related.
• Add nostr_filter_clone() and NIP-18 repost support #52: Modifies filter cloning/matching code; this PR extends that logic to include search cloning and cleanup.
• feat: Add Relay Support #10: Prior changes to the relay filter API/matching that this PR builds upon.

Poem

🐰 I sniffed the relay and found a thread,
A curious search string where events are led,
Filters lean closer, callbacks hop in tune,
Tests hum softly beneath the moon,
Hooray for NIP‑50 — nibble, then sprint.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and accurately summarizes the main change—adding NIP-50 search filter support—which is the primary objective across all modified files.

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✨ Finishing touches

• 📝 Generate docstrings

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@tests/test_nip50.c`:
- Around line 59-66: The TEST_ASSERT_EQUAL_STRING macro can dereference NULL via
strcmp; update the macro (TEST_ASSERT_EQUAL_STRING) to first check if either
expected or actual is NULL, handle cases where both are NULL (treat as equal) or
one is NULL (log which side is NULL), set g_test_failed = 1 and return, and only
call strcmp when both pointers are non-NULL so no undefined behavior occurs.

🧹 Nitpick comments (2)

src/relay_filter.c (1)

437-447: Consider documenting the silent failure when callback is NULL but search is specified.

When a filter has a non-empty search field but search_cb is NULL, the function returns false. While this is a reasonable defensive behavior, it may silently fail from the caller's perspective if they forget to provide a callback for a filter with search.

Consider whether logging a warning or documenting this behavior more explicitly would help developers debug issues where filters unexpectedly don't match.

tests/test_nip50.c (1)

167-186: Test test_filter_clone_with_search has a subtle memory safety concern.

The test sets src.kinds to point to a stack-allocated array (int32_t kinds[] = {1}). While this works because nostr_filter_clone copies the data and the stack array remains valid throughout the function, this pattern could be fragile if the test structure changes. Also, nostr_filter_free is only called on dst, not src, which is correct here since src uses stack memory for most fields, but src.search is heap-allocated and properly freed.

The test is correct as written, but consider adding a comment explaining the intentional partial initialization for clarity.

[wksantiago]

@coderabbitai review

[coderabbitai]

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@tests/test_nip50.c`:
- Around line 161-173: Capture and assert the result of nostr_filter_parse in
test_filter_get_search before using the filter; e.g., store its return in a
variable (rc) and add an assertion that parsing succeeded (use
TEST_ASSERT_TRUE(rc == 0) or TEST_ASSERT_EQUAL_INT(0, rc) depending on the
project's convention) prior to calling nostr_filter_get_search,
nostr_filter_has_search, and nostr_filter_free.

[wksantiago]

@coderabbitai review

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Review triggered.

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