":null,"usage":{"input_tokens":4,"cache_creation_input_tokens":1065,"cache_read_input_tokens":73857,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":1065},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CYaLwToUUdw2v2yHZE6Qj","type":"assistant","uuid":"509e88b3-9345-4e0f-a1d0-074d3040b898","timestamp":"2026-02-28T10:55:19.093Z"}
{"parentUuid":"509e88b3-9345-4e0f-a1d0-074d3040b898","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"progress","data":{"type":"hook_progress","hookEvent":"PreToolUse","hookName":"PreToolUse:Bash","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/pretooluse.py"},"toolUseID":"toolu_019D2ddiYkMEYRAXd7SCNsbb","parentToolUseID":"toolu_019D2ddiYkMEYRAXd7SCNsbb","uuid":"f774b2ad-ad05-4f8c-8f2e-d4783a9d7d55","timestamp":"2026-02-28T10:55:19.100Z"}
{"parentUuid":"f774b2ad-ad05-4f8c-8f2e-d4783a9d7d55","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","message":{"model":"claude-haiku-4-5-20251001","id":"msg_01Tbg1i6ALhF1U6FeNnuUJXN","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01WcHXcCywPk8GV5AzbQAJYQ","name":"Bash","input":{"command":"grep -A 2 -B 2 \"read_line\" /home/josie/development/archlinux/packaging/paru/src/resolver.rs"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":4,"cache_creation_input_tokens":1065,"cache_read_input_tokens":73857,"output_tokens":187,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":1065,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CYaLwToUUdw2v2yHZE6Qj","type":"assistant","uuid":"350d536d-0300-4a4d-8d59-695e42a355c0","timestamp":"2026-02-28T10:55:19.139Z"}
{"parentUuid":"350d536d-0300-4a4d-8d59-695e42a355c0","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"progress","data":{"type":"hook_progress","hookEvent":"PreToolUse","hookName":"PreToolUse:Bash","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/pretooluse.py"},"toolUseID":"toolu_01WcHXcCywPk8GV5AzbQAJYQ","parentToolUseID":"toolu_01WcHXcCywPk8GV5AzbQAJYQ","uuid":"866d6563-cd96-4ad3-b212-14df79c7cd70","timestamp":"2026-02-28T10:55:19.142Z"}
{"parentUuid":"866d6563-cd96-4ad3-b212-14df79c7cd70","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"progress","data":{"type":"hook_progress","hookEvent":"PostToolUse","hookName":"PostToolUse:Bash","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/posttooluse.py"},"parentToolUseID":"toolu_019D2ddiYkMEYRAXd7SCNsbb","toolUseID":"toolu_019D2ddiYkMEYRAXd7SCNsbb","timestamp":"2026-02-28T10:55:19.176Z","uuid":"df0fa157-e859-4358-b84d-c7310e3f54f5"}
{"parentUuid":"509e88b3-9345-4e0f-a1d0-074d3040b898","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_019D2ddiYkMEYRAXd7SCNsbb","type":"tool_result","content":"    let stdin = stdin();\n    let mut input = String::new();\n    let _ = stdin.read_line(&mut input);\n    let input = input.to_lowercase();\n    let input = input.trim();\n--\n    let stdin = stdin();\n    let mut input = String::new();\n    let _ = stdin.read_line(&mut input);\n    input\n}\n--\n            let stdin = stdin();\n            let mut stdin = stdin.lock();\n            let _ = stdin.read_line(&mut input);\n        }","is_error":false}]},"uuid":"cc3584fc-eaeb-412c-a88d-6303953304b4","timestamp":"2026-02-28T10:55:19.174Z","sourceToolAssistantUUID":"509e88b3-9345-4e0f-a1d0-074d3040b898"}
{"parentUuid":"cc3584fc-eaeb-412c-a88d-6303953304b4","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"progress","data":{"type":"hook_progress","hookEvent":"PostToolUse","hookName":"PostToolUse:Bash","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/posttooluse.py"},"parentToolUseID":"toolu_01WcHXcCywPk8GV5AzbQAJYQ","toolUseID":"toolu_01WcHXcCywPk8GV5AzbQAJYQ","timestamp":"2026-02-28T10:55:19.205Z","uuid":"6f8031a6-78d7-47ec-a664-e5ae25039c0c"}
{"parentUuid":"350d536d-0300-4a4d-8d59-695e42a355c0","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01WcHXcCywPk8GV5AzbQAJYQ","type":"tool_result","content":"            input.clear();\n            if !no_confirm {\n                let _ = stdin.read_line(&mut input);\n            }","is_error":false}]},"uuid":"a0a85903-3308-4284-a11a-16601288b38b","timestamp":"2026-02-28T10:55:19.202Z","sourceToolAssistantUUID":"350d536d-0300-4a4d-8d59-695e42a355c0"}
{"parentUuid":"a0a85903-3308-4284-a11a-16601288b38b","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","message":{"model":"claude-haiku-4-5-20251001","id":"msg_01LemSGcLseU2qjG2y6H4rcp","type":"message","role":"assistant","content":[{"type":"text","text":"Now let me verify the exact context around those patterns by looking at the surrounding code more carefully:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":5,"cache_creation_input_tokens":435,"cache_read_input_tokens":74922,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":435},"output_tokens":4,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CYaLwf1vD7EHeyg653sNg","type":"assistant","uuid":"537bf969-809e-4036-8aa1-e61bff6186ee","timestamp":"2026-02-28T10:55:20.431Z"}
{"parentUuid":"537bf969-809e-4036-8aa1-e61bff6186ee","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","message":{"model":"claude-haiku-4-5-20251001","id":"msg_01LemSGcLseU2qjG2y6H4rcp","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01AarNHpYYUJtTbcPNBPqQMa","name":"Read","input":{"file_path":"/home/josie/development/archlinux/packaging/paru/src/util.rs","offset":117,"limit":35},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":5,"cache_creation_input_tokens":435,"cache_read_input_tokens":74922,"output_tokens":128,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":435,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CYaLwf1vD7EHeyg653sNg","type":"assistant","uuid":"9431be0f-fee1-491c-8c8a-ff9a1cae9101","timestamp":"2026-02-28T10:55:20.788Z"}
{"parentUuid":"9431be0f-fee1-491c-8c8a-ff9a1cae9101","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"progress","data":{"type":"hook_progress","hookEvent":"PreToolUse","hookName":"PreToolUse:Read","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/pretooluse.py"},"toolUseID":"toolu_01AarNHpYYUJtTbcPNBPqQMa","parentToolUseID":"toolu_01AarNHpYYUJtTbcPNBPqQMa","uuid":"7879abd1-acb6-49ec-bcc8-dc00c9df71e2","timestamp":"2026-02-28T10:55:20.791Z"}
{"parentUuid":"7879abd1-acb6-49ec-bcc8-dc00c9df71e2","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"progress","data":{"type":"hook_progress","hookEvent":"PostToolUse","hookName":"PostToolUse:Read","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/posttooluse.py"},"parentToolUseID":"toolu_01AarNHpYYUJtTbcPNBPqQMa","toolUseID":"toolu_01AarNHpYYUJtTbcPNBPqQMa","timestamp":"2026-02-28T10:55:20.838Z","uuid":"1f3c0c82-baa1-40c7-9aba-92674de9b25a"}
{"parentUuid":"1f3c0c82-baa1-40c7-9aba-92674de9b25a","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"progress","data":{"type":"hook_progress","hookEvent":"PostToolUse","hookName":"PostToolUse:Read","command":"callback"},"parentToolUseID":"toolu_01AarNHpYYUJtTbcPNBPqQMa","toolUseID":"toolu_01AarNHpYYUJtTbcPNBPqQMa","timestamp":"2026-02-28T10:55:20.838Z","uuid":"286892bf-c9b6-4cf5-a9e2-33f7b5d8a719"}
{"parentUuid":"9431be0f-fee1-491c-8c8a-ff9a1cae9101","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01AarNHpYYUJtTbcPNBPqQMa","type":"tool_result","content":"   117→pub fn ask(config: &Config, question: &str, default: bool) -> bool {\n   118→    let action = config.color.action;\n   119→    let bold = config.color.bold;\n   120→    let yn = if default {\n   121→        tr!(\"[Y/n]:\")\n   122→    } else {\n   123→        tr!(\"[y/N]:\")\n   124→    };\n   125→    print!(\n   126→        \"{} {} {} \",\n   127→        action.paint(\"::\"),\n   128→        bold.paint(question),\n   129→        bold.paint(yn)\n   130→    );\n   131→    let _ = stdout().lock().flush();\n   132→    if config.no_confirm {\n   133→        println!();\n   134→        return default;\n   135→    }\n   136→    let stdin = stdin();\n   137→    let mut input = String::new();\n   138→    let _ = stdin.read_line(&mut input);\n   139→    let input = input.to_lowercase();\n   140→    let input = input.trim();\n   141→\n   142→    if input == tr!(\"y\") || input == tr!(\"yes\") {\n   143→        true\n   144→    } else if input.trim().is_empty() {\n   145→        default\n   146→    } else {\n   147→        false\n   148→    }\n   149→}\n   150→\n   151→pub fn input(config: &Config, question: &str) -> String {"}]},"uuid":"63bbbcac-98ce-4306-80e2-7b0f68f0763f","timestamp":"2026-02-28T10:55:20.837Z","sourceToolAssistantUUID":"9431be0f-fee1-491c-8c8a-ff9a1cae9101"}
{"parentUuid":"63bbbcac-98ce-4306-80e2-7b0f68f0763f","isSidechain":true,"userType":"external","cwd":"/home/josie/development/archlinux/packaging/paru","sessionId":"3a514b9b-0b59-4550-843d-1322db2c248a","version":"2.1.62","gitBranch":"master","agentId":"a0576f340b5101810","slug":"replicated-weaving-peacock","message":{"model":"claude-haiku-4-5-20251001","id":"msg_018puvikKamTzDWG5MhWnXVn","type":"message","role":"assistant","content":[{"type":"text","text":"Perfect! Now I have all the information I need. Let me create a comprehensive report of my findings.\n\n## COMPREHENSIVE INVESTIGATION REPORT: Ctrl+D EOF BUG IN PARU\n\n### ROOT CAUSE IDENTIFIED\n\nThe bug is in how `read_line()` handles EOF. When EOF is reached (Ctrl+D), `read_line()` returns successfully with an **empty string** (no newline), which makes the code unable to distinguish between:\n- User pressing Ctrl+D (EOF) → empty string\n- User pressing Enter with no input → empty string\n\n**The three functions that have this vulnerability are:**\n\n---\n\n### 1. `ask()` Function\n**File:** `/home/josie/development/archlinux/packaging/paru/src/util.rs` (lines 117-149)\n\n```rust\npub fn ask(config: &Config, question: &str, default: bool) -> bool {\n    // ... prompt code ...\n    if config.no_confirm {\n        println!();\n        return default;\n    }\n    let stdin = stdin();\n    let mut input = String::new();\n    let _ = stdin.read_line(&mut input);  // LINE 138\n    let input = input.to_lowercase();\n    let input = input.trim();\n\n    if input == tr!(\"y\") || input == tr!(\"yes\") {\n        true\n    } else if input.trim().is_empty() {\n        default  // LINE 145: RETURNS DEFAULT ON EMPTY INPUT\n    } else {\n        false\n    }\n}\n```\n\n**The Bug:** Lines 138-145\n- When Ctrl+D (EOF) is pressed, `read_line()` returns empty string\n- Line 144 checks `if input.trim().is_empty()` which is TRUE for EOF\n- Line 145 returns `default` value\n- Since most `ask()` calls use `default=true`, EOF is treated as \"yes\"\n\n---\n\n### 2. `input()` Function\n**File:** `/home/josie/development/archlinux/packaging/paru/src/util.rs` (lines 151-165)\n\n```rust\npub fn input(config: &Config, question: &str) -> String {\n    // ... prompt code ...\n    if config.no_confirm {\n        println!();\n        return \"\".into();\n    }\n    let stdin = stdin();\n    let mut input = String::new();\n    let _ = stdin.read_line(&mut input);  // LINE 163\n    input\n}\n```\n\n**The Bug:** Line 163\n- Returns empty string on EOF\n- Caller treats empty string as \"no input\" (see line 534 in search.rs)\n\n---\n\n### 3. `get_provider()` Function\n**File:** `/home/josie/development/archlinux/packaging/paru/src/util.rs` (lines 296-337)\n\n```rust\npub fn get_provider(max: usize, no_confirm: bool) -> usize {\n    let mut input = String::new();\n\n    loop {\n        print!(\"\\n{}\", tr!(\"Enter a number (default=1): \"));\n        let _ = stdout().lock().flush();\n        input.clear();\n\n        if !no_confirm {\n            let stdin = stdin();\n            let mut stdin = stdin.lock();\n            let _ = stdin.read_line(&mut input);  // LINE 307\n        }\n\n        let num = input.trim();\n        if num.is_empty() {\n            return 0;  // LINE 312: RETURNS DEFAULT ON EMPTY\n        }\n        // ... validation ...\n    }\n}\n```\n\n**The Bug:** Lines 307-312\n- On EOF, `read_line()` returns empty string\n- Line 311-312 treats empty as \"return default\"\n- Default is 0 (first provider)\n\n---\n\n### 4. Raw `read_line()` Call in Group Selection\n**File:** `/home/josie/development/archlinux/packaging/paru/src/resolver.rs` (lines 114-120)\n\n```rust\ninput.clear();\nif !no_confirm {\n    let _ = stdin.read_line(&mut input);  // LINE 117\n}\n\nlet menu = NumberMenu::new(input.trim());\n```\n\n**The Bug:** Lines 116-120\n- Part of resolver's group callback (called during dependency resolution)\n- On EOF, `input` is empty\n- `NumberMenu::new(\"\")` selects \"all\" (default behavior)\n- This means EOF = select all packages in group\n\n---\n\n### CALL SITES OF `ask()` FUNCTION\n\n| File | Line | Context | `default` Value | Expected EOF Behavior |\n|------|------|---------|-----------------|----------------------|\n| `src/util.rs` | def @ 117 | Function definition | - | Abort |\n| `src/install.rs` | 172 | \"Proceed with installation?\" | `true` | Abort, not yes |\n| `src/install.rs` | 1111 | \"Remove make dependencies?\" | `false` | Abort, not no |\n| `src/install.rs` | 1124 | \"Proceed to review?\" | `true` | Abort, not yes |\n| `src/install.rs` | 1127 | \"Proceed with installation?\" | `true` | Abort, not yes |\n| `src/install.rs` | 1203 | \"Build them anyway?\" | `true` | Abort, not yes |\n| `src/install.rs` | 1719 | \"Accept changes?\" | `true` | Abort, not yes |\n| `src/install.rs` | 1790 | \"Accept changes?\" (diff) | `true` | Abort, not yes |\n| `src/clean.rs` | 43 | \"Clean AUR packages?\" | `!remove_all` | Abort |\n| `src/clean.rs` | 50 | \"Remove saved diffs?\" | `true` | Abort, not yes |\n| `src/repo.rs` | 354 | \"Proceed with removal?\" | `true` | Abort, not yes |\n| `src/keys.rs` | 67 | \"import?\" | `true` | Abort, not yes |\n\n**Pattern:** 11 of 12 call sites use `default=true`, meaning EOF defaults to accepting/yes. Only one uses `default=false`.\n\n---\n\n### CALL SITES OF `input()` FUNCTION\n\n| File | Line | Context | Expected EOF Behavior |\n|------|------|---------|----------------------|\n| `src/util.rs` | def @ 151 | Function definition | Abort |\n| `src/search.rs` | 529 | \"Packages to install\" | Return empty string |\n| `src/search.rs` | 531 | \"Select packages\" | Return empty string |\n| `src/upgrade.rs` | 400 | \"Packages to exclude\" | Return empty string |\n\n**Pattern:** Returns empty string on EOF, which callers interpret as \"no selection\" (benign).\n\n---\n\n### DIRECT `read_line()` CALLS BYPASSING `ask()`/`input()`\n\n1. **Resolver group callback** - `/home/josie/development/archlinux/packaging/paru/src/resolver.rs`, lines 111-120\n   - Used during group expansion\n   - EOF → empty → selects all packages (default)\n\n2. **Provider selection in alpm callback** - `/home/josie/development/archlinux/packaging/paru/src/config.rs`, line 1209\n   - Calls `get_provider()` which has same bug\n   - EOF → returns 0 (first provider)\n\n---\n\n### `no_confirm` INTERACTION\n\nThe `no_confirm` flag **does not bypass read entirely** for all functions:\n\n1. **`ask()` function** (line 132-135 in util.rs):\n   - If `no_confirm=true`: Returns `default` **without reading**\n   - This is correct - skips interactive prompt\n\n2. **`input()` function** (line 157-160 in util.rs):\n   - If `no_confirm=true`: Returns `\"\"` **without reading**\n   - This is correct - skips interactive prompt\n\n3. **`get_provider()` function** (lines 304-308 in util.rs):\n   - If `no_confirm=true`: **Skips read_line call**\n   - Returns default (0)\n\n4. **Resolver group callback** (lines 116-118 in resolver.rs):\n   - If `no_confirm=true`: **Skips read_line call**\n   - Uses empty input (selects all)\n\n**Conclusion:** `no_confirm` works correctly - it prevents reading. The bug is when reading **does happen** and EOF is reached.\n\n---\n\n### ERROR HANDLING PATTERNS\n\n**Critical Finding:** All 5 `read_line()` calls ignore errors:\n\n```rust\nlet _ = stdin.read_line(&mut input);  // Discards Result\n```\n\nThe `read_line()` method returns `io::Result<usize>`:\n- `Ok(0)` = EOF reached\n- `Ok(n)` = n bytes read (including newline)\n- `Err(e)` = I/O error\n\n**All 5 locations discard this return value**, making it impossible to distinguish EOF from normal input at the call site.\n\n---\n\n### TESTING FINDINGS\n\n**No existing tests for EOF behavior:**\n- `/home/josie/development/archlinux/packaging/paru/tests/common/tests.rs` - No tests for `ask()` or `input()`\n- Tests use mock framework but no stdin EOF tests\n- All test cases use `--noconfirm` flag (which avoids the bug)\n\n---\n\n### SUMMARY OF VULNERABLE LOCATIONS\n\n| Function | File | Line | Vulnerable Pattern | Impact |\n|----------|------|------|-------------------|--------|\n| `ask()` | util.rs | 138 | Ignores EOF in return value | **HIGH**: Treats EOF as default |\n| `input()` | util.rs | 163 | Ignores EOF in return value | **LOW**: Returns empty string |\n| `get_provider()` | util.rs | 307 | Ignores EOF in return value | **HIGH**: Treats EOF as provider 0 |\n| Group callback | resolver.rs | 117 | Ignores EOF in return value | **HIGH**: Treats EOF as \"select all\" |\n| Config question CB | config.rs | 1209 | Calls `get_provider()` | **HIGH**: Inherited from get_provider |\n\n---\n\n### KEY TECHNICAL INSIGHT\n\nThe root issue is that `read_line()` doesn't distinguish between:\n\n```rust\n// User presses Enter (yields \"\\n\")\nstdin.read_line(&mut input) → Ok(1), input = \"\\n\"\ninput.trim() → \"\" ✓ Correct: empty input detected\n\n// User presses Ctrl+D (EOF, yields \"\")\nstdin.read_line(&mut input) → Ok(0), input = \"\"\ninput.trim() → \"\" ✓ WRONG: Indistinguishable from Enter\n```\n\nThe return value of `read_line()` (0 = EOF, >0 = bytes read) is discarded with `let _`, so EOF cannot be detected."}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":804,"cache_read_input_tokens":75357,"output_tokens":2698,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":804,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CYaLwmoTBUPrZEQJrq4DG","type":"assistant","uuid":"686bda9d-709c-4fcf-91c5-76c6fbcb0179","timestamp":"2026-02-28T10:55:42.621Z"}
