feat(drift): use adaptive sampling rate by default

[devin-ai-integration]

Summary

Update setup agent prompts and onboard wizards to use adaptive sampling mode as the default, while also allowing users to choose fixed mode.

What changed

Agent prompts (phase_create_config.md, phase_cloud_configure_recording.md): Config templates now output recording.sampling.mode: adaptive with base_rate instead of the flat sampling_rate field. The customization flow includes sampling mode selection (adaptive or fixed).

Onboard wizard (onboard/config.go): Recording struct uses nested RecordingSampling with mode: adaptive and base_rate. Generated configs use the new structure.

Cloud wizard (onboard-cloud/):

• RecordingConfigTable now includes a "Sampling Mode" row that toggles between adaptive/fixed
• SaveRecordingConfig accepts a samplingMode parameter (defaults to adaptive if empty, validates allowed values)
• Review step summary shows the selected sampling mode
• Existing config's sampling mode is loaded from raw YAML to avoid config parser normalization

Agent tool (cloud_save_config): Schema updated with optional sampling_mode enum parameter (adaptive/fixed). SaveCloudConfig passes mode through to SaveRecordingConfig.

Config (config.go): Exported FindConfigFile() for raw YAML inspection by the cloud wizard.

Why

Adaptive sampling automatically reduces recording rate under load, which reduces performance overhead for high-traffic services. Making it the default ensures new setups get this benefit without manual configuration, while still allowing users to opt into fixed mode when they need predictable sampling.

Fixes #223

Review & Testing Checklist for Human

• Run tusk init and verify generated .tusk/config.yaml contains recording.sampling.mode: adaptive and recording.sampling.base_rate: 1 instead of flat sampling_rate
• Run cloud onboard wizard and verify the recording config table shows "Sampling Mode" row that toggles between adaptive/fixed
• Test the cloud wizard with fixed mode selected and verify the saved config reflects mode: fixed
• Re-run the cloud wizard on a legacy config (without explicit sampling.mode) and verify it defaults to adaptive, not fixed

Notes

• The cloud wizard preserves the legacy sampling_rate field alongside the new nested fields for backward compatibility with older SDK versions.
• SaveRecordingConfig defaults to adaptive if an empty mode string is passed and validates that mode is one of adaptive/fixed.
• loadExistingConfig reads the raw YAML to check if sampling.mode was explicitly set, avoiding the config parser's normalization of absent mode to "fixed".

Link to Devin session: https://app.devin.ai/sessions/82231cf6c58342128ed7bf072ea79f1c
Requested by: @jy-tan

[devin-ai-integration]

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[cubic-dev-ai]

1 issue found across 7 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="internal/agent/prompts/phase_cloud_configure_recording.md">

<violation number="1" location="internal/agent/prompts/phase_cloud_configure_recording.md:45">
P2: The customization flow documents `fixed` sampling mode but never asks the user to choose a mode, so `fixed` cannot be selected.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review, or fix all with cubic.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cubic-dev-ai]

2 issues found across 10 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="internal/tui/onboard-cloud/save.go">

<violation number="1" location="internal/tui/onboard-cloud/save.go:216">
P2: Validate `samplingMode` before writing it to config; unsupported values can be persisted as-is and create invalid recording settings.</violation>
</file>

<file name="internal/tui/onboard-cloud/helpers.go">

<violation number="1" location="internal/tui/onboard-cloud/helpers.go:199">
P2: The empty-string check here is unreachable: the config parser already normalizes an absent `sampling.mode` to `"fixed"` during validation. For pre-existing configs without an explicit mode, `cfg.Recording.Sampling.Mode` will be `"fixed"` (not `""`), so this fallback to `"adaptive"` never triggers. To honour the PR's intent of defaulting to adaptive, this should check for `"fixed"` when the config file doesn't actually contain the field (e.g., check whether the raw YAML key was present), or default at the point before the config parser normalizes it.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review, or fix all with cubic.}