fix(ci): skip the flash comment for sub-30 B deltas and agent-doc changes (#28806)

The commit hash compiled into px4_firmware_version_binary() changes its code size, so a PR with no code change reported -8 B on v6x and got a comment. Changes that only touch agent instructions also no longer build the targets.

Assisted-by: Claude:claude-opus-5-5

Signed-off-by: Jacob Dahl <dahl.jakejacob@gmail.com>

.github/workflows/flash_analysis.yml

@@ -11,11 +11,19 @@ on:
       - 'main'
     paths-ignore:
       - 'docs/**'
+      - '.agents/**'
+      - '.claude/**'
+      - '**/AGENTS.md'
+      - '**/CLAUDE.md'
   pull_request:
     branches:
       - '**'
     paths-ignore:
       - 'docs/**'
+      - '.agents/**'
+      - '.claude/**'
+      - '**/AGENTS.md'
+      - '**/CLAUDE.md'
 
 jobs:
   analyze_flash:

Tools/ci/firmware_size.py

@@ -7,6 +7,10 @@ import os
 from pathlib import Path
 import subprocess
 
+# The commit hash compiled into px4_firmware_version_binary() changes its code
+# size, so identical sources on two commits can differ by up to 16 B.
+MIN_REPORTED_DELTA = 30
+
 
 def memory_usage(elf: Path) -> dict[str, int]:
     # Sections rather than program headers: ld may map the ELF header into the
@@ -67,7 +71,8 @@ def summarize(before: dict[str, int], after: dict[str, int]) -> dict:
     return {
         "flash": format_change(before["flash"], after["flash"]),
         "ram": format_change(before["ram"], after["ram"]),
-        "changed": before != after,
+        "changed": any(abs(after[key] - before[key]) >= MIN_REPORTED_DELTA
+                       for key in ("flash", "ram")),
     }
 
 

Tools/ci/test_firmware_size.py

@@ -110,6 +110,11 @@ SECTIONS
         self.assertFalse(summarize({"flash": 1, "ram": 0}, {"flash": 1, "ram": 0})["changed"])
         self.assertEqual(format_change(0, 4488), "🔴 +4,488 B (n/a)")
 
+    def test_small_deltas_are_not_reported(self):
+        before = {"flash": 1000, "ram": 1000}
+        self.assertFalse(summarize(before, {"flash": 992, "ram": 1029})["changed"])
+        self.assertTrue(summarize(before, {"flash": 970, "ram": 1000})["changed"])
+
     def test_change_indicator(self):
         for delta, expected in ((1001, "🔴 "), (1000, "🟡 "), (101, "🟡 "), (100, ""),
                                 (-100, ""), (-101, "🟢 "), (-5000, "🟢 ")):