Sync anthropics/claude-code submodule to v2.1.77 and add --effort flag support

[Copilot]

Upstream anthropics/claude-code advanced from v2.1.70 (da80366) to v2.1.77 (079dc85). The notable SDK-relevant addition in this range is the --effort CLI flag (documented in v2.1.72 changelog), which was previously unsupported in the C# SDK.

Submodule

• Bumped submodules/anthropic-claude-code from da80366 → 079dc85 (v2.1.77)

New: --effort flag support

Effort levels from the CLI (low, medium, high, auto) are now expressible via a typed enum.

• Added EffortLevel enum (Auto, Low, Medium, High) to ThreadOptions.cs
• Added Effort property to both ThreadOptions and ClaudeExecArgs
• Added ToCliValue(EffortLevel) extension in ClaudeCliValueExtensions.cs (follows existing PermissionMode/SettingSource pattern)
• Emits --effort <value> in ClaudeExec.BuildCommandArgs after --model
• Propagated from ThreadOptions → ClaudeExecArgs in ClaudeThread

var thread = client.CreateThread(new ThreadOptions
{
    Model = ClaudeModels.ClaudeOpus45,
    Effort = EffortLevel.High,
});

Tests

• 5 new unit tests in ClaudeExecTests covering each effort level and the omitted-effort case

Original prompt

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This section details on the original issue you should resolve

<issue_title>Sync Claude Code upstream changes (da80366 -> 6f049b6)</issue_title>
<issue_description>

Detected upstream updates in anthropics/claude-code affecting Claude Code CLI surface tracking.

Runtime source of truth for this SDK is the real print-mode CLI contract:

• claude -p --output-format json

• claude -p --output-format stream-json --verbose

• Submodule path: submodules/anthropic-claude-code

• Published CLI package used in CI: @anthropic-ai/claude-code

• Watched branch: main

• Current pinned commit: da80366c484698e6370ad9e8abf121f33f8f79e0

• Latest upstream commit: 6f049b620f6066c5246b922dc7360371fe33c826

• Compare: anthropics/claude-code@da80366...6f049b6

• Latest commit: anthropics/claude-code@6f049b6

Changed files (CLI-relevant)

• CHANGELOG.md

Potential CLI flag changes from diff

• --agents
• --compact
• --continue
• --effort
• --git
• --model
• --plugin-dir
• --print
• --resume

Potential model changes from diff

• claude-code
• claude-opus-4-5

Potential feature changes from diff

• (no feature tokens detected from diff)

Commits

• 6f049b6 chore: Update CHANGELOG.md (2026-03-12)
• 45b5430 chore: Update CHANGELOG.md (2026-03-11)
• f6dbf44 chore: Update CHANGELOG.md (2026-03-10)
• 540b61b chore: Update CHANGELOG.md (2026-03-10)
• 00553de chore: Update CHANGELOG.md (2026-03-10)
• 53a5f3e chore: Update CHANGELOG.md (2026-03-07)

Action required

• Pull the new anthropics/claude-code submodule commit into this repository
• Validate latest claude --help output and representative non-interactive runtime behavior
• Re-check claude -p --output-format json and claude -p --output-format stream-json --verbose payload shape
• Sync C# SDK constants/options/models with upstream CLI changes
• Add or update tests for new flags/models/features
• Update docs (README + docs/Features + docs/Architecture if needed)

Opened automatically by scheduled workflow 'Claude Code Upstream Watch'.</issue_description>

<agent_instructions>Check and update code if needed but create just one. Branch and on pr </agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Sync Claude Code upstream changes (da80366 -> 6f049b6) #4

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