Reduce default context_lines to 5 to reduce noisy diff context

README.md

@@ -133,8 +133,8 @@ require("ai_commit_msg").setup({
   -- Show notifications
   notifications = true,
 
-  -- Number of surrounding lines to include in git diff (default: 10)
-  context_lines = 10,
+  -- Number of surrounding lines to include in git diff (default: 5)
+  context_lines = 5,
 
   -- Cost display format ("compact", "verbose", or false to disable)
   cost_display = "compact",
@@ -361,6 +361,10 @@ git config --global core.editor nvim
 - If you don't specify `max_tokens`, the model will use its default limit
 - For Anthropic models, `max_tokens` is required by the API
   (defaults to 1000 if not specified)
+- For more predictable messages, keep `context_lines` modest (default `5`;
+  usually `3-10`) to reduce noisy, unchanged context in large diffs
+- If outputs are too verbose, prefer single-line defaults with a custom
+  `system_prompt` that only allows a body for complex or breaking changes
 
 ## License
 

doc/ai-commit-msg.nvim.txt

@@ -162,8 +162,8 @@ CONFIGURATION            *ai-commit-msg.nvim-ai-commit-msg.nvim-configuration*
       -- Show notifications
       notifications = true,
 
-      -- Number of surrounding lines to include in git diff (default: 10)
-      context_lines = 10,
+      -- Number of surrounding lines to include in git diff (default: 5)
+      context_lines = 5,
 
       -- Cost display format ("compact", "verbose", or false to disable)
       cost_display = "compact",
@@ -421,6 +421,10 @@ TIPS                              *ai-commit-msg.nvim-ai-commit-msg.nvim-tips*
 - If you don’t specify `max_tokens`, the model will use its default limit
 - For Anthropic models, `max_tokens` is required by the API
     (defaults to 1000 if not specified)
+- For more predictable messages, keep `context_lines` modest (default `5`;
+  usually `3-10`) to reduce noisy, unchanged context in large diffs
+- If outputs are too verbose, prefer single-line defaults with a custom
+  `system_prompt` that only allows a body for complex or breaking changes
 
 
 LICENSE                        *ai-commit-msg.nvim-ai-commit-msg.nvim-license*

lua/ai_commit_msg/config.lua

@@ -42,7 +42,7 @@ M.default = {
   },
   spinner = true,
   notifications = true,
-  context_lines = 10,
+  context_lines = 5,
   keymaps = {
     quit = "q", -- Set to false to disable
   },

lua/ai_commit_msg/prompts.lua

@@ -1,7 +1,7 @@
 local M = {}
 
 M.DEFAULT_SYSTEM_PROMPT = [[
-# System Prompt: Conventional Commits Auto-Commit Generator (Bullet-Style Bodies)
+# System Prompt: Conventional Commit Generator (Concise-First)
 
 You are to produce a single Conventional Commit message that strictly adheres to
 Conventional Commits 1.0.0. Multi-line bodies should use plain ASCII bullet
@@ -92,12 +92,19 @@ Validation rules:
 - No emojis.
 - Keep to ASCII where possible.
 
+Default style preference (important):
+- Prefer a single-line header by default.
+- Only add a body when it materially improves clarity (complex/multi-area work,
+  important rationale, notable behavior change, or migration steps).
+- If you add a body, keep it compact (usually 2-4 bullets).
+
 When to use multi-line commits (with bullet-style body and/or footers):
 - Use a bullet-style body when:
   - The change is non-trivial and benefits from concise highlights
   - There are user-visible behavior or UX changes
   - Complex refactors, performance work, or architectural changes need rationale
   - You modified multiple areas and want to call out secondary impacts
+  - The commit would be ambiguous as a single-line header
 - Use footers when:
   - There is a breaking change (mandatory: add "!" in header and a BREAKING CHANGE footer)
   - You need to reference actual issues, tickets, PRs, or include co-authors (only if specific numbers/names exist)
@@ -117,6 +124,7 @@ Task:
 5) Group similar or related changes together - don't list every minor modification separately.
 6) If multiple independent changes are present, summarize the primary one; do NOT emit multiple commits.
 7) The final output must contain exactly one commit (one header). No prefaces, no postfaces, no explanations.
+8) Default to a single-line header unless body/footer information is genuinely useful.
 
 Return ONLY the commit message.
 Do NOT include multiple commits. Do NOT include any other text.