Make stream key (path) optional, defaulting to empty broadcast

[kixelated]

The Path field on the MoQ service was effectively required: if a user
left it blank, obs_service_get_connect_info could return null, which
the output then assigned to a std::string — undefined behaviour that
manifested as a hang at start-of-stream.

• Treat the key/path as optional and default to "" via get_defaults.
• Null-guard the values returned by obs_data_get_string and
  obs_service_get_connect_info before assigning to std::string.
• Relabel the property as "Path (optional)" in the UI.

https://claude.ai/code/session_01AH2RwNCd5nPs8hNHYmMv97

[coderabbitai]

Walkthrough

This pull request enhances NULL safety in the MoQ service implementation and adds support for default settings. Changes include: guarding against NULL results when retrieving server URL and stream key in MoQOutput::Start(), adding a new Defaults() function to register default settings values, updating the Update() function to safely read string settings with null checks, and registering a new get_defaults callback in the service info. Additionally, the UI label for the key field is updated from "Path" to "Path (optional)" for clarity.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly describes the main change: making the stream key/path optional with empty string defaults, which aligns with the primary objective of the PR.
Description check	✅ Passed	The description is directly related to the changeset, explaining the problem being solved and the specific changes made across all modified files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/optional-stream-key-r7er0

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/optional-stream-key-r7er0

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[coderabbitai]

🧹 Nitpick comments (2)

src/moq-service.cpp (2)

21-25: 💤 Low value

Defaults() sets empty-string defaults that are already the libobs fallback.

obs_data_set_default_string(settings, "server", "") and the "key" counterpart are no-ops in practice — obs_data_get_string already falls back to "" for unset keys. The real value of registering get_defaults is framework-level (OBS resets and profile creation), but a non-trivial default (e.g., a placeholder URL) would give this more practical benefit. As-is it's harmless but worth reconsidering if a sensible default server URL exists for this backend.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/moq-service.cpp` around lines 21 - 25, The Defaults method currently
calls obs_data_set_default_string(settings, "server", "") and
obs_data_set_default_string(settings, "key", "") which are no-ops because
obs_data_get_string already defaults to ""—either remove these lines (or the
Defaults override) or set a non-trivial default value; update
MoQService::Defaults to either drop the empty-string defaults or replace the
"server" default with a sensible placeholder URL (e.g., "https://example.com")
and populate "key" with a meaningful placeholder if appropriate so the
get_defaults call provides practical benefit.

---

14-19: 💤 Low value

obs_data_get_string does not return NULL for a valid obs_data_t *.

The null checks (server_value ? server_value : "") in Update() are safe but likely redundant. Per OBS libobs convention, obs_data_get_string returns "" — not NULL — when a key is missing from a valid obs_data_t object. The actual null risk that was causing the hang lived in obs_service_get_connect_info() (now guarded in moq-output.cpp). These guards in Update() don't hurt, but they may mislead future readers into thinking this API can return NULL.

Does obs_data_get_string return NULL or empty string when the key is not found in libobs?

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/moq-service.cpp` around lines 14 - 19, The Update() method currently does
redundant NULL checks around obs_data_get_string (server_value and key_value)
even though obs_data_get_string returns an empty string for missing keys;
simplify by assigning server and path directly from obs_data_get_string without
the ternary fallbacks (refer to Update(), server, path, and obs_data_get_string)
and keep the real NULL guard that was added around
obs_service_get_connect_info() in moq-output.cpp to handle the actual null risk.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@src/moq-service.cpp`:
- Around line 21-25: The Defaults method currently calls
obs_data_set_default_string(settings, "server", "") and
obs_data_set_default_string(settings, "key", "") which are no-ops because
obs_data_get_string already defaults to ""—either remove these lines (or the
Defaults override) or set a non-trivial default value; update
MoQService::Defaults to either drop the empty-string defaults or replace the
"server" default with a sensible placeholder URL (e.g., "https://example.com")
and populate "key" with a meaningful placeholder if appropriate so the
get_defaults call provides practical benefit.
- Around line 14-19: The Update() method currently does redundant NULL checks
around obs_data_get_string (server_value and key_value) even though
obs_data_get_string returns an empty string for missing keys; simplify by
assigning server and path directly from obs_data_get_string without the ternary
fallbacks (refer to Update(), server, path, and obs_data_get_string) and keep
the real NULL guard that was added around obs_service_get_connect_info() in
moq-output.cpp to handle the actual null risk.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: a773c95e-cc9f-4628-8b9e-423d1d06b449

📥 Commits

Reviewing files that changed from the base of the PR and between ae7df7a and 4714a35.

📒 Files selected for processing (3)

• src/moq-output.cpp
• src/moq-service.cpp
• src/moq-service.h