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+---
+epic: 11
+story: 11.2
+title: "Pipe / Stdin Mode"
+status: draft
+---
+
+## Epic 11 — CLI Tool
+**Goal:** Command-line tool for scripting and automation, same Rust engine.
+
+### Story 11.2: Pipe / Stdin Mode
+
+As a developer,
+I want to pipe input into CalcPad from other commands,
+So that I can integrate calculations into shell scripts and pipelines.
+
+**Acceptance Criteria:**
+
+**Given** the user pipes a single expression to calcpad
+**When** they run `echo "100 USD in EUR" | calcpad`
+**Then** the converted value is printed to stdout
+**And** the process exits with code 0
+
+**Given** the user pipes multi-line input to calcpad
+**When** they run `cat mysheet.cp | calcpad` or pipe multiple lines via heredoc
+**Then** each line is evaluated as part of a sheet (variables carry forward between lines)
+**And** each line's result is printed on a corresponding output line
+
+**Given** stdin contains a mix of expressions, comments, and blank lines
+**When** calcpad processes the input
+**Then** comments and blank lines produce empty output lines
+**And** expressions produce their computed results on the corresponding lines