sentry: Log the Nix command / subcommand

[edolstra]

Motivation

Improve Sentry crash reports.

Note: this only include the command/subcommand (e.g. nix flake update), but no other command-line arguments.

Context

Summary by CodeRabbit

• Chores
  • Enhanced error-tracking so reports include the invoked command name.
  • Added subcommand path context to diagnostics so errors show the full nested command invoked.
  • Adjusted command-path collection to ensure subcommand context is captured consistently, improving issue visibility.

[coderabbitai]

📝 Walkthrough

Walkthrough

Sentry initialization now sets a nix_command tag from the executable basename. Subcommand derivation from the CLI MultiCommand is moved to run before the helpRequested early return, and when Sentry is enabled a nix_subcommand tag is set with the space-separated subcommand path.

Changes

Cohort / File(s)	Summary
Sentry Tagging & CLI ordering src/nix/main.cc	Set nix_command (exec basename) during Sentry init; moved nested subcommand derivation earlier (before args.helpRequested) and removed prior help-scoped derivation; set nix_subcommand tag under HAVE_SENTRY with space-separated subcommand path.

Sequence Diagram(s)

(No sequence diagram generated — change is a localized reorder and tagging in a single source file.)

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• Fix chroot helper with Sentry #433: Modifies Sentry-related initialization and startup sequencing in src/nix/main.cc.
• Input::getAccessorUnchecked(): Wrap fetches in a path lock #410: Related CLI/startup ordering changes affecting initialization paths.
• When doing concurrent substitutions of the same path, download only once #398: Prior adjustments to diagnostic tagging and early-return behavior in main startup flow.

Suggested reviewers

• cole-h

Poem

🐰
I hopped through argv and found my trail,
Basename here, subcommands set like a sail.
Sentry listens with tags all neat,
Tracking each hop of my tiny feet. 🥕

🚥 Pre-merge checks | ✅ 4 | ❌ 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 (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: logging Nix command and subcommand information to Sentry for improved crash reporting.
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 sentry-log-command

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[github-actions]

🚀 Deployed on https://69ea593dd3c4c800a86a407d--determinate-nix.netlify.app

[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/nix/main.cc`:
- Line 417: The sentry_set_tag call is tagging nix_command with argv[0] which
can be a full path and leak user-specific data; update the code in main (where
sentry_set_tag is called) to normalize argv[0] to the executable basename before
tagging (e.g., use std::filesystem::path(argc>0?argv[0]:"").filename().string()
or an equivalent basename/libgen approach) and pass that basename string into
sentry_set_tag instead of the raw argv[0].

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

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

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 3f580517-f889-44f9-b635-c0d4a2851e5e

📥 Commits

Reviewing files that changed from the base of the PR and between 0c00b00 and 2e25546.

📒 Files selected for processing (1)

• src/nix/main.cc

[coderabbitai]

🧹 Nitpick comments (1)

src/nix/main.cc (1)

573-581: Minor: Redundant null check for command.

The condition command && on line 576 is redundant since the while (command) loop condition on line 575 already guarantees command is non-null when entering the loop body.

Proposed simplification

 std::vector<std::string> subcommand;
 MultiCommand * command = &args;
 while (command) {
-    if (command && command->command) {
+    if (command->command) {
         subcommand.push_back(command->command->first);
         command = dynamic_cast<MultiCommand *>(&*command->command->second);
     } else
         break;
 }

🤖 Prompt for AI Agents

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

In `@src/nix/main.cc` around lines 573 - 581, The if condition inside the while
loop redundantly checks `command` even though the loop `while (command)` already
ensures it's non-null; update the loop body in function using `MultiCommand *
command = &args` to remove the redundant `command &&` and just test `if
(command->command)` (or equivalently `if (command->command) { ... } else
break;`) when pushing into `subcommand` and performing the `dynamic_cast` to the
next `MultiCommand`.

🤖 Prompt for all review comments with AI agents

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

Nitpick comments:
In `@src/nix/main.cc`:
- Around line 573-581: The if condition inside the while loop redundantly checks
`command` even though the loop `while (command)` already ensures it's non-null;
update the loop body in function using `MultiCommand * command = &args` to
remove the redundant `command &&` and just test `if (command->command)` (or
equivalently `if (command->command) { ... } else break;`) when pushing into
`subcommand` and performing the `dynamic_cast` to the next `MultiCommand`.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: ccfe4473-9597-4763-8ad0-54f9fc994225

📥 Commits

Reviewing files that changed from the base of the PR and between 2e25546 and 6196dc2.

📒 Files selected for processing (1)

• src/nix/main.cc